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• Oracle Coherence, Split-Brain and Recovery Protocols In Detail

  - by Ricardo Ferreira

  This article provides a high level conceptual overview of Split-Brain scenarios in distributed systems. It will focus on a specific example of cluster communication failure and recovery in Oracle Coherence. This includes a discussion on the witness protocol (used to remove failed cluster members) and the panic protocol (used to resolve Split-Brain scenarios). Note that the removal of cluster members does not necessarily indicate a Split-Brain condition. Oracle Coherence does not (and cannot) detect a Split-Brain as it occurs, the condition is only detected when cluster members that previously lost contact with each other regain contact. Cluster Topology and Configuration In order to create an good didactic for the article, let's assume a cluster topology and configuration. In this example we have a six member cluster, consisting of one JVM on each physical machine. The member IDs are as follows: Member ID  IP Address  1  10.149.155.76  2  10.149.155.77  3  10.149.155.236  4  10.149.155.75  5  10.149.155.79  6  10.149.155.78 Members 1, 2, and 3 are connected to a switch, and members 4, 5, and 6 are connected to a second switch. There is a link between the two switches, which provides network connectivity between all of the machines. Member 1 is the first member to join this cluster, thus making it the senior member. Member 6 is the last member to join this cluster. Here is a log snippet from Member 6 showing the complete member set: 2010-02-26 15:27:57.390/3.062 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=6): Started DefaultCacheServer... SafeCluster: Name=cluster:0xDDEB Group{Address=224.3.5.3, Port=35465, TTL=4} MasterMemberSet ( ThisMember=Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) OldestMember=Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ActualMemberSet=MemberSet(Size=6, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) RecycleMillis=120000 RecycleSet=MemberSet(Size=0, BitSetCount=0 ) ) At approximately 15:30, the connection between the two switches is severed: Thirty seconds later (the default packet timeout in development mode) the logs indicate communication failures across the cluster. In this example, the communication failure was caused by a network failure. In a production setting, this type of communication failure can have many root causes, including (but not limited to) network failures, excessive GC, high CPU utilization, swapping/virtual memory, and exceeding maximum network bandwidth. In addition, this type of failure is not necessarily indicative of a split brain. Any communication failure will be logged in this fashion. Member 2 logs a communication failure with Member 5: 2010-02-26 15:30:32.638/196.928 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) ) The Coherence clustering protocol (TCMP) is a reliable transport mechanism built on UDP. In order for the protocol to be reliable, it requires an acknowledgement (ACK) for each packet delivered. If a packet fails to be acknowledged within the configured timeout period, the Coherence cluster member will log a packet timeout (as seen in the log message above). When this occurs, the cluster member will consult with other members to determine who is at fault for the communication failure. If the witness members agree that the suspect member is at fault, the suspect is removed from the cluster. If the witnesses unanimously disagree, the accuser is removed. This process is known as the witness protocol. Since Member 2 cannot communicate with Member 5, it selects two witnesses (Members 1 and 4) to determine if the communication issue is with Member 5 or with itself (Member 2). However, Member 4 is on the switch that is no longer accessible by Members 1, 2 and 3; thus a packet timeout for member 4 is recorded as well: 2010-02-26 15:30:35.648/199.938 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) Member 1 has the ability to confirm the departure of member 4, however Member 6 cannot as it is also inaccessible. At the same time, Member 3 sends a request to remove Member 6, which is followed by a report from Member 3 indicating that Member 6 has departed the cluster: 2010-02-26 15:30:35.706/199.996 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft request for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) 2010-02-26 15:30:35.709/199.999 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft notification for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) The log for Member 3 determines how Member 6 departed the cluster: 2010-02-26 15:30:35.161/191.694 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=3): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ) 2010-02-26 15:30:35.165/191.698 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=3): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ); removing Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) In this case, Member 3 happened to select two witnesses that it still had connectivity with (Members 1 and 2) thus resulting in a simple decision to remove Member 6. Given the departure of Member 6, Member 2 is left with a single witness to confirm the departure of Member 4: 2010-02-26 15:30:35.713/200.003 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=2): Member departure confirmed by MemberSet(Size=1, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ); removing Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) In the meantime, Member 4 logs a missing heartbeat from the senior member. This message is also logged on Members 5 and 6. 2010-02-26 15:30:07.906/150.453 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=PacketListenerN, member=4): Scheduled senior member heartbeat is overdue; rejoining multicast group. Next, Member 4 logs a TcpRing failure with Member 2, thus resulting in the termination of Member 2: 2010-02-26 15:30:21.421/163.968 Oracle Coherence GE 3.5.3/465p2 <D4> (thread=Cluster, member=4): TcpRing: Number of socket exceptions exceeded maximum; last was "java.net.SocketTimeoutException: connect timed out"; removing the member: 2 For quick process termination detection, Oracle Coherence utilizes a feature called TcpRing which is a sparse collection of TCP/IP-based connections between different members in the cluster. Each member in the cluster is connected to at least one other member, which (if at all possible) is running on a different physical box. This connection is not used for any data transfer, only heartbeat communications are sent once a second per each link. If a certain number of exceptions are thrown while trying to re-establish a connection, the member throwing the exceptions is removed from the cluster. Member 5 logs a packet timeout with Member 3 and cites witnesses Members 4 and 6: 2010-02-26 15:30:29.791/165.037 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=5): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) 2010-02-26 15:30:29.798/165.044 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=5): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ); removing Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Eventually we are left with two distinct clusters consisting of Members 1, 2, 3 and Members 4, 5, 6, respectively. In the latter cluster, Member 4 is promoted to senior member. The connection between the two switches is restored at 15:33. Upon the restoration of the connection, the cluster members immediately receive cluster heartbeats from the two senior members. In the case of Members 1, 2, and 3, the following is logged: 2010-02-26 15:33:14.970/369.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): The member formerly known as Member(Id=4, Timestamp=2010-02-26 15:30:35.341, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. Likewise for Members 4, 5, and 6: 2010-02-26 15:33:14.343/336.890 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=4): The member formerly known as Member(Id=1, Timestamp=2010-02-26 15:30:31.64, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. This message indicates that a senior heartbeat is being received from members that were previously removed from the cluster, in other words, something that should not be possible. For this reason, the recipients of these messages will initially ignore them. After several iterations of these messages, the existence of multiple clusters is acknowledged, thus triggering the panic protocol to reconcile this situation. When the presence of more than one cluster (i.e. Split-Brain) is detected by a Coherence member, the panic protocol is invoked in order to resolve the conflicting clusters and consolidate into a single cluster. The protocol consists of the removal of smaller clusters until there is one cluster remaining. In the case of equal size clusters, the one with the older Senior Member will survive. Member 1, being the oldest member, initiates the protocol: 2010-02-26 15:33:45.970/400.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): An existence of a cluster island with senior Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) containing 3 nodes have been detected. Since this Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) is the senior of an older cluster island, the panic protocol is being activated to stop the other island's senior and all junior nodes that belong to it. Member 3 receives the panic: 2010-02-26 15:33:45.803/382.336 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=3): Received panic from senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) caused by Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member 4, the senior member of the younger cluster, receives the kill message from Member 3: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. In turn, Member 4 requests the departure of its junior members 5 and 6: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:43.343/349.015 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=6): Received a Kill message from a valid Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer); stopping cluster service. Once Members 4, 5, and 6 restart, they rejoin the original cluster with senior member 1. The log below is from Member 4. Note that it receives a different member id when it rejoins the cluster. 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:46.921/369.468 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Service Cluster left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:InvocationService, member=4): Service InvocationService left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=OptimisticCache, member=4): Service OptimisticCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=ReplicatedCache, member=4): Service ReplicatedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=DistributedCache, member=4): Service DistributedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:Management, member=4): Service Management left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service Management with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service DistributedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service ReplicatedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service OptimisticCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service InvocationService with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member(Id=6, Timestamp=2010-02-26 15:33:47.046, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) left Cluster with senior member 4 2010-02-26 15:33:49.218/371.765 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=n/a): Restarting cluster 2010-02-26 15:33:49.421/371.968 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=n/a): Service Cluster joined the cluster with senior service member n/a 2010-02-26 15:33:49.625/372.172 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=n/a): This Member(Id=5, Timestamp=2010-02-26 15:33:50.499, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=1) joined cluster "cluster:0xDDEB" with senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=2) Cool isn't it?

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• Creating STA COM compatible ASP.NET Applications

  - by Rick Strahl

  When building ASP.NET applications that interface with old school COM objects like those created with VB6 or Visual FoxPro (MTDLL), it's extremely important that the threads that are serving requests use Single Threaded Apartment Threading. STA is a COM built-in technology that allows essentially single threaded components to operate reliably in a multi-threaded environment. STA's guarantee that COM objects instantiated on a specific thread stay on that specific thread and any access to a COM object from another thread automatically marshals that thread to the STA thread. The end effect is that you can have multiple threads, but a COM object instance lives on a fixed never changing thread. ASP.NET by default uses MTA (multi-threaded apartment) threads which are truly free spinning threads that pay no heed to COM object marshaling. This is vastly more efficient than STA threading which has a bit of overhead in determining whether it's OK to run code on a given thread or whether some sort of thread/COM marshaling needs to occur. MTA COM components can be very efficient, but STA COM components in a multi-threaded environment always tend to have a fair amount of overhead. It's amazing how much COM Interop I still see today so while it seems really old school to be talking about this topic, it's actually quite apropos for me as I have many customers using legacy COM systems that need to interface with other .NET applications. In this post I'm consolidating some of the hacks I've used to integrate with various ASP.NET technologies when using STA COM Components. STA in ASP.NET Support for STA threading in the ASP.NET framework is fairly limited. Specifically only the original ASP.NET WebForms technology supports STA threading directly via its STA Page Handler implementation or what you might know as ASPCOMPAT mode. For WebForms running STA components is as easy as specifying the ASPCOMPAT attribute in the @Page tag:<%@ Page Language="C#" AspCompat="true" %> which runs the page in STA mode. Removing it runs in MTA mode. Simple. Unfortunately all other ASP.NET technologies built on top of the core ASP.NET engine do not support STA natively. So if you want to use STA COM components in MVC or with class ASMX Web Services, there's no automatic way like the ASPCOMPAT keyword available. So what happens when you run an STA COM component in an MTA application? In low volume environments - nothing much will happen. The COM objects will appear to work just fine as there are no simultaneous thread interactions and the COM component will happily run on a single thread or multiple single threads one at a time. So for testing running components in MTA environments may appear to work just fine. However as load increases and threads get re-used by ASP.NET COM objects will end up getting created on multiple different threads. This can result in crashes or hangs, or data corruption in the STA components which store their state in thread local storage on the STA thread. If threads overlap this global store can easily get corrupted which in turn causes problems. STA ensures that any COM object instance loaded always stays on the same thread it was instantiated on. What about COM+? COM+ is supposed to address the problem of STA in MTA applications by providing an abstraction with it's own thread pool manager for COM objects. It steps in to the COM instantiation pipeline and hands out COM instances from its own internally maintained STA Thread pool. This guarantees that the COM instantiation threads are STA threads if using STA components. COM+ works, but in my experience the technology is very, very slow for STA components. It adds a ton of overhead and reduces COM performance noticably in load tests in IIS. COM+ can make sense in some situations but for Web apps with STA components it falls short. In addition there's also the need to ensure that COM+ is set up and configured on the target machine and the fact that components have to be registered in COM+. COM+ also keeps components up at all times, so if a component needs to be replaced the COM+ package needs to be unloaded (same is true for IIS hosted components but it's more common to manage that). COM+ is an option for well established components, but native STA support tends to provide better performance and more consistent usability, IMHO. STA for non supporting ASP.NET Technologies As mentioned above only WebForms supports STA natively. However, by utilizing the WebForms ASP.NET Page handler internally it's actually possible to trick various other ASP.NET technologies and let them work with STA components. This is ugly but I've used each of these in various applications and I've had minimal problems making them work with FoxPro STA COM components which is about as dififcult as it gets for COM Interop in .NET. In this post I summarize several STA workarounds that enable you to use STA threading with these ASP.NET Technologies: ASMX Web Services ASP.NET MVC WCF Web Services ASP.NET Web API ASMX Web Services I start with classic ASP.NET ASMX Web Services because it's the easiest mechanism that allows for STA modification. It also clearly demonstrates how the WebForms STA Page Handler is the key technology to enable the various other solutions to create STA components. Essentially the way this works is to override the WebForms Page class and hijack it's init functionality for processing requests. Here's what this looks like for Web Services:namespace FoxProAspNet { public class WebServiceStaHandler : System.Web.UI.Page, IHttpAsyncHandler { protected override void OnInit(EventArgs e) { IHttpHandler handler = new WebServiceHandlerFactory().GetHandler( this.Context, this.Context.Request.HttpMethod, this.Context.Request.FilePath, this.Context.Request.PhysicalPath); handler.ProcessRequest(this.Context); this.Context.ApplicationInstance.CompleteRequest(); } public IAsyncResult BeginProcessRequest( HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } } public class AspCompatWebServiceStaHandlerWithSessionState : WebServiceStaHandler, IRequiresSessionState { } } This class overrides the ASP.NET WebForms Page class which has a little known AspCompatBeginProcessRequest() and AspCompatEndProcessRequest() method that is responsible for providing the WebForms ASPCOMPAT functionality. These methods handle routing requests to STA threads. Note there are two classes - one that includes session state and one that does not. If you plan on using ASP.NET Session state use the latter class, otherwise stick to the former. This maps to the EnableSessionState page setting in WebForms. This class simply hooks into this functionality by overriding the BeginProcessRequest and EndProcessRequest methods and always forcing it into the AspCompat methods. The way this works is that BeginProcessRequest() fires first to set up the threads and starts intializing the handler. As part of that process the OnInit() method is fired which is now already running on an STA thread. The code then creates an instance of the actual WebService handler factory and calls its ProcessRequest method to start executing which generates the Web Service result. Immediately after ProcessRequest the request is stopped with Application.CompletRequest() which ensures that the rest of the Page handler logic doesn't fire. This means that even though the fairly heavy Page class is overridden here, it doesn't end up executing any of its internal processing which makes this code fairly efficient. In a nutshell, we're highjacking the Page HttpHandler and forcing it to process the WebService process handler in the context of the AspCompat handler behavior. Hooking up the Handler Because the above is an HttpHandler implementation you need to hook up the custom handler and replace the standard ASMX handler. To do this you need to modify the web.config file (here for IIS 7 and IIS Express): <configuration> <system.webServer> <handlers> <remove name="WebServiceHandlerFactory-Integrated-4.0" /> <add name="Asmx STA Web Service Handler" path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" precondition="integrated"/> </handlers> </system.webServer> </configuration> (Note: The name for the WebServiceHandlerFactory-Integrated-4.0 might be slightly different depending on your server version. Check the IIS Handler configuration in the IIS Management Console for the exact name or simply remove the handler from the list there which will propagate to your web.config). For IIS 5 & 6 (Windows XP/2003) or the Visual Studio Web Server use:<configuration> <system.web> <httpHandlers> <remove path="*.asmx" verb="*" /> <add path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" /> </httpHandlers> </system.web></configuration> To test, create a new ASMX Web Service and create a method like this: [WebService(Namespace = "http://foxaspnet.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class FoxWebService : System.Web.Services.WebService { [WebMethod] public string HelloWorld() { return "Hello World. Threading mode is: " + System.Threading.Thread.CurrentThread.GetApartmentState(); } } Run this before you put in the web.config configuration changes and you should get: Hello World. Threading mode is: MTA Then put the handler mapping into Web.config and you should see: Hello World. Threading mode is: STA And you're on your way to using STA COM components. It's a hack but it works well! I've used this with several high volume Web Service installations with various customers and it's been fast and reliable. ASP.NET MVC ASP.NET MVC has quickly become the most popular ASP.NET technology, replacing WebForms for creating HTML output. MVC is more complex to get started with, but once you understand the basic structure of how requests flow through the MVC pipeline it's easy to use and amazingly flexible in manipulating HTML requests. In addition, MVC has great support for non-HTML output sources like JSON and XML, making it an excellent choice for AJAX requests without any additional tools. Unlike WebForms ASP.NET MVC doesn't support STA threads natively and so some trickery is needed to make it work with STA threads as well. MVC gets its handler implementation through custom route handlers using ASP.NET's built in routing semantics. To work in an STA handler requires working in the Page Handler as part of the Route Handler implementation. As with the Web Service handler the first step is to create a custom HttpHandler that can instantiate an MVC request pipeline properly:public class MvcStaThreadHttpAsyncHandler : Page, IHttpAsyncHandler, IRequiresSessionState { private RequestContext _requestContext; public MvcStaThreadHttpAsyncHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); _requestContext = requestContext; } public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } protected override void OnInit(EventArgs e) { var controllerName = _requestContext.RouteData.GetRequiredString("controller"); var controllerFactory = ControllerBuilder.Current.GetControllerFactory(); var controller = controllerFactory.CreateController(_requestContext, controllerName); if (controller == null) throw new InvalidOperationException("Could not find controller: " + controllerName); try { controller.Execute(_requestContext); } finally { controllerFactory.ReleaseController(controller); } this.Context.ApplicationInstance.CompleteRequest(); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } public override void ProcessRequest(HttpContext httpContext) { throw new NotSupportedException("STAThreadRouteHandler does not support ProcessRequest called (only BeginProcessRequest)"); } } This handler code figures out which controller to load and then executes the controller. MVC internally provides the information needed to route to the appropriate method and pass the right parameters. Like the Web Service handler the logic occurs in the OnInit() and performs all the processing in that part of the request. Next, we need a RouteHandler that can actually pick up this handler. Unlike the Web Service handler where we simply registered the handler, MVC requires a RouteHandler to pick up the handler. RouteHandlers look at the URL's path and based on that decide on what handler to invoke. The route handler is pretty simple - all it does is load our custom handler: public class MvcStaThreadRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); return new MvcStaThreadHttpAsyncHandler(requestContext); } } At this point you can instantiate this route handler and force STA requests to MVC by specifying a route. The following sets up the ASP.NET Default Route:Route mvcRoute = new Route("{controller}/{action}/{id}", new RouteValueDictionary( new { controller = "Home", action = "Index", id = UrlParameter.Optional }), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute);   To make this code a little easier to work with and mimic the behavior of the routes.MapRoute() functionality extension method that MVC provides, here is an extension method for MapMvcStaRoute(): public static class RouteCollectionExtensions { public static void MapMvcStaRoute(this RouteCollection routeTable, string name, string url, object defaults = null) { Route mvcRoute = new Route(url, new RouteValueDictionary(defaults), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute); } } With this the syntax to add  route becomes a little easier and matches the MapRoute() method:RouteTable.Routes.MapMvcStaRoute( name: "Default", url: "{controller}/{action}/{id}", defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional } ); The nice thing about this route handler, STA Handler and extension method is that it's fully self contained. You can put all three into a single class file and stick it into your Web app, and then simply call MapMvcStaRoute() and it just works. Easy! To see whether this works create an MVC controller like this: public class ThreadTestController : Controller { public string ThreadingMode() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Try this test both with only the MapRoute() hookup in the RouteConfiguration in which case you should get MTA as the value. Then change the MapRoute() call to MapMvcStaRoute() leaving all the parameters the same and re-run the request. You now should see STA as the result. You're on your way using STA COM components reliably in ASP.NET MVC. WCF Web Services running through IIS WCF Web Services provide a more robust and wider range of services for Web Services. You can use WCF over HTTP, TCP, and Pipes, and WCF services support WS* secure services. There are many features in WCF that go way beyond what ASMX can do. But it's also a bit more complex than ASMX. As a basic rule if you need to serve straight SOAP Services over HTTP I 'd recommend sticking with the simpler ASMX services especially if COM is involved. If you need WS* support or want to serve data over non-HTTP protocols then WCF makes more sense. WCF is not my forte but I found a solution from Scott Seely on his blog that describes the progress and that seems to work well. I'm copying his code below so this STA information is all in one place and quickly explain. Scott's code basically works by creating a custom OperationBehavior which can be specified via an [STAOperation] attribute on every method. Using his attribute you end up with a class (or Interface if you separate the contract and class) that looks like this: [ServiceContract] public class WcfService { [OperationContract] public string HelloWorldMta() { return Thread.CurrentThread.GetApartmentState().ToString(); } // Make sure you use this custom STAOperationBehavior // attribute to force STA operation of service methods [STAOperationBehavior] [OperationContract] public string HelloWorldSta() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Pretty straight forward. The latter method returns STA while the former returns MTA. To make STA work every method needs to be marked up. The implementation consists of the attribute and OperationInvoker implementation. Here are the two classes required to make this work from Scott's post:public class STAOperationBehaviorAttribute : Attribute, IOperationBehavior { public void AddBindingParameters(OperationDescription operationDescription, System.ServiceModel.Channels.BindingParameterCollection bindingParameters) { } public void ApplyClientBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.ClientOperation clientOperation) { // If this is applied on the client, well, it just doesn’t make sense. // Don’t throw in case this attribute was applied on the contract // instead of the implementation. } public void ApplyDispatchBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.DispatchOperation dispatchOperation) { // Change the IOperationInvoker for this operation. dispatchOperation.Invoker = new STAOperationInvoker(dispatchOperation.Invoker); } public void Validate(OperationDescription operationDescription) { if (operationDescription.SyncMethod == null) { throw new InvalidOperationException("The STAOperationBehaviorAttribute " + "only works for synchronous method invocations."); } } } public class STAOperationInvoker : IOperationInvoker { IOperationInvoker _innerInvoker; public STAOperationInvoker(IOperationInvoker invoker) { _innerInvoker = invoker; } public object[] AllocateInputs() { return _innerInvoker.AllocateInputs(); } public object Invoke(object instance, object[] inputs, out object[] outputs) { // Create a new, STA thread object[] staOutputs = null; object retval = null; Thread thread = new Thread( delegate() { retval = _innerInvoker.Invoke(instance, inputs, out staOutputs); }); thread.SetApartmentState(ApartmentState.STA); thread.Start(); thread.Join(); outputs = staOutputs; return retval; } public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state) { // We don’t handle async… throw new NotImplementedException(); } public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result) { // We don’t handle async… throw new NotImplementedException(); } public bool IsSynchronous { get { return true; } } } The key in this setup is the Invoker and the Invoke method which creates a new thread and then fires the request on this new thread. Because this approach creates a new thread for every request it's not super efficient. There's a bunch of overhead involved in creating the thread and throwing it away after each thread, but it'll work for low volume requests and insure each thread runs in STA mode. If better performance is required it would be useful to create a custom thread manager that can pool a number of STA threads and hand off threads as needed rather than creating new threads on every request. If your Web Service needs are simple and you need only to serve standard SOAP 1.x requests, I would recommend sticking with ASMX services. It's easier to set up and work with and for STA component use it'll be significantly better performing since ASP.NET manages the STA thread pool for you rather than firing new threads for each request. One nice thing about Scotts code is though that it works in any WCF environment including self hosting. It has no dependency on ASP.NET or WebForms for that matter. STA - If you must STA components are a  pain in the ass and thankfully there isn't too much stuff out there anymore that requires it. But when you need it and you need to access STA functionality from .NET at least there are a few options available to make it happen. Each of these solutions is a bit hacky, but they work - I've used all of them in production with good results with FoxPro components. I hope compiling all of these in one place here makes it STA consumption a little bit easier. I feel your pain :-) Resources Download STA Handler Code Examples Scott Seely's original STA WCF OperationBehavior Article© Rick Strahl, West Wind Technologies, 2005-2012Posted in FoxPro   ASP.NET  .NET  COM   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• EMERGENCY - Major Problems After Perl Module Installed via WHM

  - by Russell C.

  I attempted to install the perl module Net::Twitter::Role::API::Lists using WHM and after doing so my whole site came down. It seems that something that was updated with the install isn't functioning correctly and since our website it written in Perl none of our site scripts will run. In almost 8 years of working with Perl I've never had any issues arise after installing a perl module so I have no idea how to even start troubleshooting. The error I see when trying to compile any of our Perl scripts is below. I'd appreciate any advice on what might be wrong and steps on how I can go about resolve it. Thanks in advance for your help! Attribute (+type_constraint) of class MooseX::AttributeHelpers::Counter has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0x9ae35b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4d7718)', 'Moose::Meta::Attribute=HASH(0x9ae35b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'undef', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 10 require MooseX/AttributeHelpers/Counter.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 23 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 Attribute (+default) of class MooseX::AttributeHelpers::Counter has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4df4b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4d7718)', 'Moose::Meta::Attribute=HASH(0xa4df4b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'undef', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 10 require MooseX/AttributeHelpers/Counter.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 23 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 Attribute (+type_constraint) of class MooseX::AttributeHelpers::Number has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4ea48c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4f778c)', 'Moose::Meta::Attribute=HASH(0xa4ea48c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'undef', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 9 require MooseX/AttributeHelpers/Number.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 24 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 Attribute (+default) of class MooseX::AttributeHelpers::Number has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4f7804)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4f778c)', 'Moose::Meta::Attribute=HASH(0xa4f7804)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'undef', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 9 require MooseX/AttributeHelpers/Number.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 24 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 Attribute (+type_constraint) of class MooseX::AttributeHelpers::String has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4fdae0)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4fd5c4)', 'Moose::Meta::Attribute=HASH(0xa4fdae0)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa5002d8)', 'Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa5002d8)', 'Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa5002d8)', 'Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4fd5c4)', 'undef', 'MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4fd5c4)', 'MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4fd5c4)', 'MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 10 require MooseX/AttributeHelpers/String.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 25 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_per

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• Java Thread Management and Application Flow

  - by user119179

  I have a Java application that downloads information (Entities) from our server. I use a Download thread to download the data. The flow of the download process is as follows: Log in - The user entity is downloaded Based on the User Entity, download a 'Community' entities List and Display in drop down Based on Community drop down selection, Download and show 'Org Tree' in a JTree Based on Node selection, download Category entities and display in drop down Based on Category selection, download Sub Category entities and display in drop down Based on Sub Category selection download a large data set and save it The download occurs in a thread so the GUI does not 'freeze'. It also allows me to update a Progress Bar. I need help with managing this process. The main problem is when I download entity data I have to find a way to wait for the thread to finish before attempting to get the entity and move to the next step in the app flow. So far I have used a modal dialog to control flow. I start the thread, pop up a modal and then dispose of the modal when the thread is finished. The modal/thread are Observer/Observable the thread does a set changed when it is finished and the dialog disposes. Displaying a modal effectively stops the flow of the application so it can wait for the download to finish. I also tried just moving all the work flow to Observers. All relevant GUI in the process are Observers. Each update method waits for the download to finish and then calls the next piece of GUI which does its own downloading. So far I found these two methods produce code that is hard to follow. I would like to 'centralize' this work flow so other developers are not pulling out their hair when they try to follow it. My Question is: Do you have any suggestions/examples where a work flow such as this can be managed in a way that produces code that is easy to follow? I know 'easy' is a relative term and I know my both my options already work but I would like to get some ideas from other coders while I still have time to change it. Thank you very much.

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• Updating a deallocated UIWebView from a background thread

  - by Dan Ray

  As you can see from the title, I've programmed myself into a corner and I've got several things working against me... In a UIViewController subclass that manages a large and complex view. One part of it is a UIWebView that contains output from a web request that I had to build and execute, and manually assemble HTML from. Since it takes a second or two to run, I dropped it into the background by calling self performSelectorInBackground:. Then from that method I call there, I use self performSelectorOnMainThread: to get back to the surface of the thread stack to update the UIWebView with what I just got. Like this (which I've cut down to show only the relevant issues): -(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { //then get mapquest directions NSLog(@"Got called to handle new location!"); [manager stopUpdatingLocation]; [self performSelectorInBackground:@selector(getDirectionsFromHere:) withObject:newLocation]; } - (void)getDirectionsFromHere:(CLLocation *)newLocation { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; CLLocationCoordinate2D here = newLocation.coordinate; // assemble a call to the MapQuest directions API in NSString *dirURL // ...cut for brevity NSLog(@"Query is %@", dirURL); NSString *response = [NSString stringWithContentsOfURL:[NSURL URLWithString:dirURL] encoding:NSUTF8StringEncoding error:NULL]; NSMutableString *directionsOutput = [[NSMutableString alloc] init]; // assemble response into an HTML table in NSString *directionsOutput // ...cut for brevity [self performSelectorOnMainThread:@selector(updateDirectionsWithHtml:) withObject:directionsOutput waitUntilDone:NO]; [directionsOutput release]; [pool drain]; [pool release]; } - (void)updateDirectionsWithHtml:(NSString *)directionsOutput { [self.directionsWebView loadHTMLString:directionsOutput baseURL:nil]; } This all works totally great, UNLESS I've backed out of this view controller before CLLocationManager hits its delegate method. If this happens after I've already left this view, I get: 2010-06-07 16:38:08.508 EverWondr[180:760b] bool _WebTryThreadLock(bool), 0x1b6830: Tried to obtain the web lock from a thread other than the main thread or the web thread. This may be a result of calling to UIKit from a secondary thread. Crashing now... Despite what this says, I can repeatably cause this crash when I back out too early. I'm not at all convinced that attempting a UI update from a background thread is really the issue; I think it's that my UIWebView is deallocated. I suspect that the fact I was just IN a background thread makes the runtime suspect something's up about that, but I feel fairly sure that's not it. So how do I tell CLLocationManager not to worry about it, when I'm backing out of that view? I tried [self.locationManager stopUpdatingLocation] inside my viewWillDisappear method, but that didn't do it. (Incidentally, MapQuest's apis are FANTASTIC. Way WAY better than anything Google provides. I can't recommend them highly enough.)

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• waiting for 2 different events in a single thread

  - by João Portela

  component A (in C++) - is blocked waiting for alarm signals (not relevant) and IO signals (1 udp socket). has one handler for each of these. component B (java) - has to receive the same information the component A udp socket receives. periodicaly gives instructions that should be sent through component A udp socket. How to join both components? it is strongly desirable that: the changes to attach component B to component A are minimal (its not my code and it is not very pleasent to mess with). the time taken by the new operations (usually communicating with component B) interfere very little with the usual processing time of component A - this means that if the operations are going to take a "some" time I would rather use a thread or something to do them. note: since component A receives udp packets more frequently that it has component B instructions to forward, if necessary, it can only forward the instructions (when available) from the IO handler. my initial ideia was to develop a component C (in C++) that would sit inside the component A code (is this called an adapter?) that when instanciated starts the java process and makes the necessary connections (that not so little overhead in the initialization is not a problem). It would have 2 stacks, one for the data to give component B (lets call it Bstack) and for the data to give component A (lets call it Astack). It would sit on its thread (lets call it new-thread) waiting for data to be available in Bstack to send it over udp, and listen on the udp socket to put data on the Astack. This means that the changes to component A are only: when it receives a new UDP packet put it on the Bstack, and if there is something on the Astack sent it over its UDP socket (I decided for this because this socket would only be used in the main thread). One of the problems is that I don't know how to wait for both of these events at the same time using only one thread. so my questions are: Do I really need to use the main thread to send the data over component A socket or can I do it from the new-thread? (I think the answer is no, but I'm not sure about race conditions on sockets) how to I wait for both events? boost::condition_variable or something similar seems the solution in the case of the stack and boost::asio::io_service io_service.run() seems like the thing to use for the socket. Is there any other alternative solution for this problem that I'm not aware of? Thanks for reading this long text but I really wanted you to understand the problem.

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• Thread class closing from other Class (Activity) with protected void onStop() Android

  - by user1761337

  I have a Problem with Closing the Thread. I will Closing the Thread with onStop,onPause and onDestroy. This is my Source in the Activity Class: @Override protected void onStop(){ super.onStop(); finish(); } @Override protected void onPause() { super.onPause(); finish(); } @Override public void onDestroy() { this.mWakeLock.release(); super.onDestroy(); } And the Thread Class: public class GameThread extends Thread { private SurfaceHolder mSurfaceHolder; private Handler mHandler; private Context mContext; private Paint mLinePaint; private Paint blackPaint; //for consistent rendering private long sleepTime; //amount of time to sleep for (in milliseconds) private long delay=1000/30; //state of game (Running or Paused). int state = 1; public final static int RUNNING = 1; public final static int PAUSED = 2; public final static int STOPED = 3; GameSurface gEngine; public GameThread(SurfaceHolder surfaceHolder, Context context, Handler handler,GameSurface gEngineS){ //data about the screen mSurfaceHolder = surfaceHolder; mHandler = handler; mContext = context; gEngine=gEngineS; } //This is the most important part of the code. It is invoked when the call to start() is //made from the SurfaceView class. It loops continuously until the game is finished or //the application is suspended. private long beforeTime; @Override public void run() { //UPDATE while (state==RUNNING) { Log.d("State","Thread is runnig"); //time before update beforeTime = System.nanoTime(); //This is where we update the game engine gEngine.Update(); //DRAW Canvas c = null; try { //lock canvas so nothing else can use it c = mSurfaceHolder.lockCanvas(null); synchronized (mSurfaceHolder) { //clear the screen with the black painter. //reset the canvas c.drawColor(Color.BLACK); //This is where we draw the game engine. gEngine.doDraw(c); } } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } this.sleepTime = delay-((System.nanoTime()-beforeTime)/1000000L); try { //actual sleep code if(sleepTime>0){ this.sleep(sleepTime); } } catch (InterruptedException ex) { Logger.getLogger(GameThread.class.getName()).log(Level.SEVERE, null, ex); } while (state==PAUSED){ Log.d("State","Thread is pausing"); try { this.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }} How i can close the Thread from Activity Class??

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• Co-worker uses ridiculous commenting convention, how to cope? [closed]

  - by Jessica Friedman

  A co-worker in the small start-up I work at writes (C++) code like this: // some class class SomeClass { // c'tor SomeClass(); // d'tor ~SomeClass(); // some function void someFunction(int x, int y); }; // some function void SomeClass::someFunction(int x, int y) { // init worker m_worker.init(); // log LOG_DEBUG("Worker initialized"); // find current cache auto it = m_currentCache.find(); // flush if (it->flush() == false) { // return return false } // return return true } This is how he writes 100% of his code: a spacer line, a useless comment which says nothing other than what is plainly stated in the following statement, and the statement itself. This is absolutely driving me insane. A simple class written by him spans 3 times as much as it's supposed to, It looks well commented but the comments contain no new information. In fact the code is completely undocumented in any normal definition of "documentation". All of the comments are just a repetition of what is written in C++ in the following line. I've confronted him several times about it and each time he seems to understand what I am saying but then goes on to not change his coding and not fix old code which is written like this. I've went on and on again and again about the distinct disadvantages of writing code like this but nothing get through to him. Other co-workers doesn't seem to mind it as much and management doesn't seem to really care. What do I do? (sorry for the rant)

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• Signals and threads - good or bad design decision?

  - by Jens

  I have to write a program that performs highly computationally intensive calculations. The program might run for several days. The calculation can be separated easily in different threads without the need of shared data. I want a GUI or a web service that informs me of the current status. My current design uses BOOST::signals2 and BOOST::thread. It compiles and so far works as expected. If a thread finished one iteration and new data is available it calls a signal which is connected to a slot in the GUI class. My question(s): Is this combination of signals and threads a wise idea? I another forum somebody advised someone else not to "go down this road". Are there potential deadly pitfalls nearby that I failed to see? Is my expectation realistic that it will be "easy" to use my GUI class to provide a web interface or a QT, a VTK or a whatever window? Is there a more clever alternative (like other boost libs) that I overlooked? following code compiles with g++ -Wall -o main -lboost_thread-mt <filename>.cpp code follows: #include <boost/signals2.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> #include <iostream> #include <iterator> #include <string> using std::cout; using std::cerr; using std::string; /** * Called when a CalcThread finished a new bunch of data. */ boost::signals2::signal<void(string)> signal_new_data; /** * The whole data will be stored here. */ class DataCollector { typedef boost::mutex::scoped_lock scoped_lock; boost::mutex mutex; public: /** * Called by CalcThreads call the to store their data. */ void push(const string &s, const string &caller_name) { scoped_lock lock(mutex); _data.push_back(s); signal_new_data(caller_name); } /** * Output everything collected so far to std::out. */ void out() { typedef std::vector<string>::const_iterator iter; for (iter i = _data.begin(); i != _data.end(); ++i) cout << " " << *i << "\n"; } private: std::vector<string> _data; }; /** * Several of those can calculate stuff. * No data sharing needed. */ struct CalcThread { CalcThread(string name, DataCollector &datcol) : _name(name), _datcol(datcol) { } /** * Expensive algorithms will be implemented here. * @param num_results how many data sets are to be calculated by this thread. */ void operator()(int num_results) { for (int i = 1; i <= num_results; ++i) { std::stringstream s; s << "["; if (i == num_results) s << "LAST "; s << "DATA " << i << " from thread " << _name << "]"; _datcol.push(s.str(), _name); } } private: string _name; DataCollector &_datcol; }; /** * Maybe some VTK or QT or both will be used someday. */ class GuiClass { public: GuiClass(DataCollector &datcol) : _datcol(datcol) { } /** * If the GUI wants to present or at least count the data collected so far. * @param caller_name is the name of the thread whose data is new. */ void slot_data_changed(string caller_name) const { cout << "GuiClass knows: new data from " << caller_name << std::endl; } private: DataCollector & _datcol; }; int main() { DataCollector datcol; GuiClass mc(datcol); signal_new_data.connect(boost::bind(&GuiClass::slot_data_changed, &mc, _1)); CalcThread r1("A", datcol), r2("B", datcol), r3("C", datcol), r4("D", datcol), r5("E", datcol); boost::thread t1(r1, 3); boost::thread t2(r2, 1); boost::thread t3(r3, 2); boost::thread t4(r4, 2); boost::thread t5(r5, 3); t1.join(); t2.join(); t3.join(); t4.join(); t5.join(); datcol.out(); cout << "\nDone" << std::endl; return 0; }

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• Application not releasing database connection Spring.net + NHibernate

  - by anupam3m

  Even after successful transaction.Application connection with the database persist.in Nhibernate log it shows Nhibernate Log 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.SessionImpl [(null)] <(null) - executing flush 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.ConnectionManager [(null)] <(null) - registering flush begin 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.ConnectionManager [(null)] <(null) - registering flush end 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.SessionImpl [(null)] <(null) - post flush 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.SessionImpl [(null)] <(null) - before transaction completion 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.ConnectionManager [(null)] <(null) - aggressively releasing database connection 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Connection.ConnectionProvider [(null)] <(null) - Closing connection 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.SessionImpl [(null)] <(null) - transaction completion 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Transaction.AdoTransaction [(null)] <(null) - running AdoTransaction.Dispose() 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.SessionImpl [(null)] <(null) - closing session 2010-05-21 14:45:08,428 [Worker] [0] DEBUG NHibernate.Impl.BatcherImpl [(null)] <(null) - running BatcherImpl.Dispose(true) Underneath given is my dataconfiguration file -- Risco.Rsp.Ac.RMAC.Mapping Risco.Rsp.Ac.Logging.Appenders -- Please help me out with this issue.Thanks

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• Thread Question

  - by Polaris

  I have method which create background thread to make some action. In this background thread I create object. But this object while creating in runtime give me an exception : The calling thread must be STA, because many UI components require this. I know that I must use Dispatcher to make reflect something to UI. But in this case I just create an object and dont iteract with UI. This is my code: public void SomeMethod() { BackgroundWorker worker = new BackgroundWorker(); worker.DoWork += new DoWorkEventHandler(Background_Method); worker.RunWorkerAsync(); } void Background_Method(object sender, DoWorkEventArgs e) { TreeView tv = new TreeView(); } How can I create objects in background thread? I use WPF application

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• Connection reset by peer: mod_fcgid: error reading data from FastCGI server Issues

  - by user145857

  Help is greatly needed for our server. We are experiencing random "Connection reset by peer: mod_fcgid: error reading data from FastCGI server" errors which cause a 500 internal server error. If the page is then reloaded it loads normally as it should. We are running MPM Worker with mod FCGID to handle PHP. We had APC cache enabled but disabled it recently to see if it would fix the problem, but the random mod FCGID errors are still continuing. No other opcode cache is active now. Our settings are below: <IfModule worker.c> MinSpareThreads 25 MaxSpareThreads 150 ThreadsPerChild 25 ThreadLimit 100 ServerLimit 700 MaxClients 700 MaxRequestsPerChild 0 </IfModule> <IfModule mod_fcgid.c> FcgidMaxRequestLen 1073741824 FcgidMaxRequestsPerProcess 2000 FcgidMaxProcessesPerClass 100 FcgidMinProcessesPerClass 0 FcgidConnectTimeout 300 FcgidIOTimeout 900 FcgidFixPathinfo 1 FcgidIdleTimeout 300 FcgidIdleScanInterval 120 FcgidBusyTimeout 300 FcgidBusyScanInterval 120 FcgidErrorScanInterval 12 FcgidZombieScanInterval 12 FcgidProcessLifeTime 3600 </IfModule> The server is a 64 core 2.1 GHZ 94 GB RAM so it has some power. Some of the fcgid timeout settings are higher because we run large reports which take up to 15 minutes. Any help is greatly appreciated! Just to clarify, the random fcgid errors are occurring when a user clicks a page on our site and the 500 error page loads instantly. This is random and occurrs less than 1% of the time but it is still an issue.

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• ThreadPool.QueueUserWorkItem new Form CreateHanle Deadlock

  - by bogdanbrudiu

  I have a thread that needs to create a popup Window. I start the thread using ThreadPool.QueueUserWorkItem(new WaitCallback(CreatePopupinThread)) Thew thread creats a new form. The application freases in the new Form constructor at CreateHandle. The Worker Thread is locked... How can I fix this?

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• Is there a straightforward way to have a ThreadStatic instance member?

  - by Dan Tao

  With the ThreadStatic attribute I can have a static member of a class with one instance of the object per thread. This is really handy for achieving thread safety using types of objects that don't guarantee thread-safe instance methods (e.g., System.Random). It only works for static members, though. Is there some corresponding attribute that provides the same functionality, but for instance members? In other words, that allows me to have one instance of the object, per thread, per instance of the containing class?

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• "The calling thread cannot access this object because a different thread owns it." While using Dispa

  - by Sdry

  I have an application, that I want to load additional xaml files, being resourcedictionaries controling the style of the application. Yet when trying to add a loaded ResourceDictionary to the mergeddictionaries I get an InvalidOperationException saying "The calling thread cannot access this object because a different thread owns it." at a point where I am not even using multiple threads. The application contains a usercontrol which loads the xaml file through a background worker, adding the loaded ResourceDictionaries to an Observablecollection. When I pass on a selected theme(=ResourceDictionary) to a function in the mainwindow of the application, it goes wrong. public void LoadTheme(Theme theme) {//sdry 2010-4-22 if(theme !=null){ this._dispatcher.Invoke(DispatcherPriority.Normal, (Action)(() => { MessageBox.Show("SKIN TEST: " + theme.Name); //> oke #if (SHOWDEBUGINFO) _selectedTheme = theme.Name; //>oke #endif Application.Current.Resources.MergedDictionaries.Clear(); //>oke Application.Current.Resources.MergedDictionaries.Add(theme.ResourceDictionary); //> InvalidOperationException //the theme object has a property named ResourceDictionary of type ResourceDictionary containing the loaded xaml })); } } My first reaction was to use the Disatcher.Invoke, even not knowing how I would not be on the gui thread, which doesn't solve a thing. So maybe my loaded theme belongs to a different thread ? but its originating from a property of a usercontrol, which should be the same thread. And its accesable untill trying to use the ResourceDictionary. This makes me confused, and not very aware of how to proceed, any help is appreciated.

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• WebClient error when using a thread in .NET

  - by Kiranu

  I'm having a very weird error using the WebClient class in .NET 4. The app simply downloads some files off the internet and provides output on a textbox (the GUI is WPF). The method that does this is the following: void DownloadFiles(object files) { fileL = (List<string>) files; foreach (string url in fileL) { byte[] data; using (System.Net.WebClient k = new WebClient()) { data = k.DownloadData(url); } //Bunch of irrelevant code goes here... } } (I added the using while trying to divine [yes I'm that desperate/ignorant] a solution, the problem happens even if the webclient is declared and initialized outside the foreach loop) Now the problem appears only when I'm executing this method on a thread separate from the WPF UI main thread. If it is executed on the UI thread then it works perfectly. When a new thread is created with: Thread t = new Thread(DownloadFiles); t.Start(files); The first time the code goes into the loop it will work, but when its the second pass inside the loop, I will always receive a TargetParameterCountException. I can't make any sense of this error. Any help is very much appreciated. EDIT Here are the Exception Details: Exception.Message = "Parameter count mismatch." Exception.InnerException = null Exception.Source = " mscorlib" The StackTrace follows: at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Delegate.DynamicInvokeImpl(Object[] args) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at FileDownloader.App.Main() in d:\mis documentos\visual studio 2010\Projects\OneMangaDownloader\FileDownloader\obj\x86\Debug\App.g.cs:line 0 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart()

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• WebClient error when using a thread in .NET 4

  - by Kiranu

  I'm having a very weird error using the WebClient class in .NET 4. The app simply downloads some files off the internet and provides output on a textbox (the GUI is WPF). The method that does this is the following: void DownloadFiles(object files) { fileL = (List<string>) files; foreach (string url in fileL) { byte[] data; using (System.Net.WebClient k = new WebClient()) { data = k.DownloadData(url); } //Bunch of irrelevant code goes here... } } (I added the using while trying to divine [yes I'm that desperate/ignorant] a solution, the problem happens even if the webclient is declared and initialized outside the foreach loop) Now the problem appears only when I'm executing this method on a thread separate from the WPF UI main thread. If it is executed on the UI thread then it works perfectly. When a new thread is created with: Thread t = new Thread(DownloadFiles); t.Start(files); The first time the code goes into the loop it will work, but when its the second pass inside the loop, I will always receive a TargetParameterCountException. I can't make any sense of this error. Any help is very much appreciated. EDIT Here are the Exception Details: Exception.Message = "Parameter count mismatch." Exception.InnerException = null Exception.Source = " mscorlib" The StackTrace follows: at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Delegate.DynamicInvokeImpl(Object[] args) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at FileDownloader.App.Main() in d:\mis documentos\visual studio 2010\Projects\OneMangaDownloader\FileDownloader\obj\x86\Debug\App.g.cs:line 0 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart()

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• terminating java applet thread on page unload

  - by Hammad Tariq

  Hello, I have got a problem here in terminating the threads. The problem is that I am using applet thread to access JS DOM and manipulate innerHTML of a span to right the Thread Name as the innerHTML. It works fine until I keep refreshing the page but if I dont give it a sleep of like 200ms and go to another page which dont have any applet on it, it will give me an error in firebug console: document.getElementById("userName") is null What I am suspecting is, although I send an interrupt on stop and I have also tried the same by setting a flag variable of running in run while loop, the thread executes much faster than the time JVM takes to unload it and I get my page changed in browser but applet is still trying to find an element with id userName. Is that true? Is there any work around of it? Is there any way to know how many threads are running at the moment? Is there any kill all command to send on destroy()? I have searched a lot, seen all the API of java threads and applets, couldn't get this to work. Below is the code: import java.applet.Applet; import netscape.javascript.*; //No need to extend JApplet, since we don't add any components; //we just paint. public class firstApplet extends Applet { /** * */ private static final long serialVersionUID = 1L; firstThread first; boolean running = false; public class firstThread extends Thread{ JSObject win; JSObject doc; firstThread second; public firstThread(JSObject window){ this.win = window; } public void run() { try{ System.out.println("running... "); while (!isInterrupted()){ doc = (JSObject) win.getMember("document"); String userName = Thread.currentThread().getName(); //String userName = "John Doe"; String S = "document.getElementById(\"userName\").innerHTML = \""+userName+"\";"; doc.eval(S); Thread.sleep(5); } }catch(Exception e){ System.out.println("exception in first thread... "); e.printStackTrace(); } } } public void init() { System.out.println("initializing... "); } public void start() { System.out.println("starting... "); JSObject window = JSObject.getWindow(this); first = new firstThread(window); first.start(); running = true; } public void stop() { first.interrupt(); first = null; System.out.println("stopping... "); } public void destroy() { if(first != null){ first = null; } System.out.println("preparing for unloading..."); } } Thanks

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• Are LinkedBlockingQueue's insert and remove methods thread safe?

  - by Steve Kuo

  I'm using LinkedBlockingQueue between two different threads. One thread adds data via add, while the other thread receives data via take. My question is, do I need to synchronize access to add and take. Is LinkedBlockingQueue's insert and remove methods thread safe?

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• Singleton again, but with multi-thread and Objective-C

  - by Tonny Xu

  I know Singleton pattern has been discussed so much. But because I'm not fully understand the memory management mechanism in Objective-C, so when I combined Singleton implementation with multithreading, I got a big error and cost me a whole day to resolve it. I had a singleton object, let's call it ObjectX. I declared an object inside ObjectX that will detach a new thread, let's call that object objectWillSpawnNewThread, when I called [[ObjectX sharedInstance].objectWillSpawnNewThread startNewThread]; The new thread could not be executed correctly, and finally I found out that I should not declare the object objectWillSpawnNewThread inside the singleton class. Here are my questions: How does Objective-C allocate static object in the memory? Where does Objective-C allocate them(Main thread stack or somewhere else)? Why would it be failed if we spawn a new thread inside the singleton object? I had searched the Objective-C language [ObjC.pdf] and Objective-C memory management document, maybe I missed something, but I currently I could not find any helpful information.

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• Apache2 MPM-prefork MPM-worker multiple instances on same Ubuntu host machine possible?

  - by user60985

  I have a live Apache2/MPM-Worker instance running Django. I want to also run an Apache2/MPM-prefork instance to run some Drupal6 applications on the same host machine and utilize a vast selection of PHP modules that run on the prefork model. I plan to use my MPM-worker instance to reverse proxy to the Apache2-prefork instance for URLS starting with myhost.com/drupal6/. It seems theoretically doable/configurable by having the second Apache2-prefork instance configured to listen on an internal port, say 127.0.0.1:8080 and having my current Apache2-worker configured to proxy pass and reverse pass to it for the 'drupal6' URLs. However, how do I compile or install the apache2-prefork version so it has a different executable name than /usr/sbin/apache2, for example /usr/sbin/apache2p, and so apache2ctl has a different name, say apache2pctl, and that apache2pctl invokes the /usr/sbin/apache2p instead of /usr/sbin/apache2... and so on down the line (eg /etc/apache2p) so I can start and restart my two instances independently? As I understand it, no one executable of 'apache2' can be compiled with both the MPM-prefork and MPM-worker modules, so it seems I need two separate versions of the apache2 MPM flavors. But then I need to invoke and control them by separate names, I assume. I looked at the configuration options for apache2 and I am a bit queasy about compiling a second apache2 version with prefork because I am not sure I can set all the options so that none of my current apache2 files is overwritten. Is there a way? Is there a standard solution to separately installing and controlling prefork and worker apache2 executables on the same machine without them stepping on each other during installation or operation?

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• Is DataRow thread safe? How to update a single datarow in a datatable using multiple threads? - .net

  - by NLV

  Hello all I want to update a single datarow in a datatable using multiple threads. Is this actually possible? I've written the following code implementing a simple multi-threading to update a single datarow. I get different results each time. Why is it so? public partial class Form1 : Form { private static DataTable dtMain; private static string threadMsg = string.Empty; public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { Thread[] thArr = new Thread[5]; dtMain = new DataTable(); dtMain.Columns.Add("SNo"); DataRow dRow; dRow = dtMain.NewRow(); dRow["SNo"] = 5; dtMain.Rows.Add(dRow); dtMain.AcceptChanges(); ThreadStart ts = new ThreadStart(delegate { dtUpdate(); }); thArr[0] = new Thread(ts); thArr[1] = new Thread(ts); thArr[2] = new Thread(ts); thArr[3] = new Thread(ts); thArr[4] = new Thread(ts); thArr[0].Start(); thArr[1].Start(); thArr[2].Start(); thArr[3].Start(); thArr[4].Start(); while (!WaitTillAllThreadsStopped(thArr)) { Thread.Sleep(500); } foreach (Thread thread in thArr) { if (thread != null && thread.IsAlive) { thread.Abort(); } } dgvMain.DataSource = dtMain; } private void dtUpdate() { for (int i = 0; i < 1000; i++) { try { dtMain.Rows[0][0] = Convert.ToInt32(dtMain.Rows[0][0]) + 1; dtMain.AcceptChanges(); } catch { continue; } } } private bool WaitTillAllThreadsStopped(Thread[] threads) { foreach (Thread thread in threads) { if (thread != null && thread.ThreadState == ThreadState.Running) { return false; } } return true; } } Any thoughts on this? Thank you NLV

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• Singleton object in IIS Web Garden

  - by Anwar Chandra

  I have a lot of Singleton implementation in asp.net application and want to move my application to IIS Web Garden environment for some performance reasons. CMIIW, moving to IIS Web Garden with n worker process, there will be one singleton object created in each worker process, which make it not a single object anymore because n 1. can I make all those singleton objects, singleton again in IIS Web Garden?

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• Apache Mod_rewrite rule working on one server, but not another

  - by Mason

  I am using mod_jk and mod_rewrite on httpd 2.2.15. I have a rule.... RewriteCond %{REQUEST_URI} !^/video/play\.xhtml.* RewriteRule ^/video/(.*) /video/play.xhtml?vid=$1 [PT] I just want to rewrite something like /video/videoidhere to /video/play.xhtml?vid=videoidhere This works perfectly on my developer machine, but on production I get a 404 (generated by Jboss, not Apache). here is the tail of access.log and rewrite.log on prod (broken). the rewrite.log is exactly the same on dev(working) applying pattern '^/video/(.*)' to uri '/video/46279d4daf5440b2844ec831413dcc3b' RewriteCond: input='/video/46279d4daf5440b2844ec831413dcc3b' pattern='!^/video/play\.xhtml.*' => matched rewrite '/video/46279d4daf5440b2844ec831413dcc3b' -> '/video/play.xhtml?vid=46279d4daf5440b2844ec831413dcc3b' split uri=/video/play.xhtml?vid=46279d4daf5440b2844ec831413dcc3b -> uri=/video/play.xhtml, args=vid=46279d4daf5440b2844ec831413dcc3b forcing '/video/play.xhtml' to get passed through to next API URI-to-filename handler "GET /video/46279d4daf5440b2844ec831413dcc3b HTTP/1.1" 404 420 "-" "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.6) Gecko/20100628 Ubuntu/10.04 (lucid) Firefox/3.6.6" I can access http://www.fivi.com/video/play.xhtml?vid=46279d4daf5440b2844ec831413dcc3b but not /video/46279d4daf5440b2844ec831413dcc3b Both server are even using the EXACT same httpd.conf, and modules. I built Apache with... ./configure --prefix /usr/local/apache2.2.15 --enable-alias --enable-rewrite --enable-cache --enable-disk_cache --enable-mem_cache --enable-ssl --enable-deflate Thanks, Mason ----UPDATE---- -mod-jk.conf JkWorkersFile /usr/local/apache2.2.15/conf/workers.properties JkLogFile /var/log/mod_jk.log JkLogLevel info JkLogStampFormat "[%a %b %d %H:%M:%S %Y]" JkOptions +ForwardKeySize +ForwardURICompatUnparsed -ForwardDirectories JkRequestLogFormat "%w %V %T" JkShmFile run/jk.shm <Location /jkstatus> JkMount status Order deny,allow Deny from all Allow from 127.0.0.1 </Location> -workers.properties worker.node1.port=8009 worker.node1.host=75.102.10.74 worker.node1.type=ajp13 worker.node1.lbfactor=20 worker.node1.ping_mode=A #As of mod_jk 1.2.27 worker.node2.port=8009 worker.node2.host=75.102.10.75 worker.node2.type=ajp13 worker.node2.lbfactor=10 worker.node2.ping_mode=A #As of mod_jk 1.2.27 worker.loadbalancer.type=lb worker.loadbalancer.balance_workers=node2,node1 worker.loadbalancer.sticky_session=True worker.status.type=status -httpd.conf ServerName www.fivi.com:80 Include /usr/local/apache2.2.15/conf/mod-jk.conf NameVirtualHost * <VirtualHost *> ServerName * DocumentRoot /usr/local/apache2/htdocs JkUnMount /* loadbalancer RedirectMatch 301 /(.*) http://www.fivi.com/$1 </VirtualHost> <VirtualHost *> ServerName www.fivi.com ServerAlias www.fivi.com images.fivi.com JkMount /* loadbalancer JkMount / loadbalancer [root@fivi conf]# /usr/local/apache2.2.15/bin/httpd -M Loaded Modules: core_module (static) authn_file_module (static) authn_default_module (static) authz_host_module (static) authz_groupfile_module (static) authz_user_module (static) authz_default_module (static) auth_basic_module (static) cache_module (static) disk_cache_module (static) mem_cache_module (static) include_module (static) filter_module (static) deflate_module (static) log_config_module (static) env_module (static) headers_module (static) setenvif_module (static) version_module (static) ssl_module (static) mpm_prefork_module (static) http_module (static) mime_module (static) status_module (static) autoindex_module (static) asis_module (static) cgi_module (static) negotiation_module (static) dir_module (static) actions_module (static) userdir_module (static) alias_module (static) rewrite_module (static) so_module (static) jk_module (shared) Syntax OK

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• Query on simple C++ threadpool implementation

  - by ticketman

  Stackoverflow has been a tremendous help to me and I'd to give something back to the community. I have been implementing a simple threadpool using the tinythread C++ portable thread library, using what I have learnt from Stackoverflow. I am new to thread programming, so not that comfortable with mutexes, etc. I have a question best asked after presenting the code (which runs quite well under Linux): // ThreadPool.h class ThreadPool { public: ThreadPool(); ~ThreadPool(); // Creates a pool of threads and gets them ready to be used void CreateThreads(int numOfThreads); // Assigns a job to a thread in the pool, but doesn't start the job // Each SubmitJob call will use up one thread of the pool. // This operation can only be undone by calling StartJobs and // then waiting for the jobs to complete. On completion, // new jobs may be submitted. void SubmitJob( void (*workFunc)(void *), void *workData ); // Begins execution of all the jobs in the pool. void StartJobs(); // Waits until all jobs have completed. // The wait will block the caller. // On completion, new jobs may be submitted. void WaitForJobsToComplete(); private: enum typeOfWorkEnum { e_work, e_quit }; class ThreadData { public: bool ready; // thread has been created and is ready for work bool haveWorkToDo; typeOfWorkEnum typeOfWork; // Pointer to the work function each thread has to call. void (*workFunc)(void *); // Pointer to work data void *workData; ThreadData() : ready(false), haveWorkToDo(false) { }; }; struct ThreadArgStruct { ThreadPool *threadPoolInstance; int threadId; }; // Data for each thread ThreadData *m_ThreadData; ThreadPool(ThreadPool const&); // copy ctor hidden ThreadPool& operator=(ThreadPool const&); // assign op. hidden // Static function that provides the function pointer that a thread can call // By including the ThreadPool instance in the void * parameter, // we can use it to access other data and methods in the ThreadPool instance. static void ThreadFuncWrapper(void *arg) { ThreadArgStruct *threadArg = static_cast<ThreadArgStruct *>(arg); threadArg->threadPoolInstance->ThreadFunc(threadArg->threadId); } // The function each thread calls void ThreadFunc( int threadId ); // Called by the thread pool destructor void DestroyThreadPool(); // Total number of threads available // (fixed on creation of thread pool) int m_numOfThreads; int m_NumOfThreadsDoingWork; int m_NumOfThreadsGivenJobs; // List of threads std::vector<tthread::thread *> m_ThreadList; // Condition variable to signal each thread has been created and executing tthread::mutex m_ThreadReady_mutex; tthread::condition_variable m_ThreadReady_condvar; // Condition variable to signal each thread to start work tthread::mutex m_WorkToDo_mutex; tthread::condition_variable m_WorkToDo_condvar; // Condition variable to signal the main thread that // all threads in the pool have completed their work tthread::mutex m_WorkCompleted_mutex; tthread::condition_variable m_WorkCompleted_condvar; }; cpp file: // // ThreadPool.cpp // #include "ThreadPool.h" // This is the thread function for each thread. // All threads remain in this function until // they are asked to quit, which only happens // when terminating the thread pool. void ThreadPool::ThreadFunc( int threadId ) { ThreadData *myThreadData = &m_ThreadData[threadId]; std::cout << "Hello world: Thread " << threadId << std::endl; // Signal that this thread is ready m_ThreadReady_mutex.lock(); myThreadData->ready = true; m_ThreadReady_condvar.notify_one(); // notify the main thread m_ThreadReady_mutex.unlock(); while(true) { //tthread::lock_guard<tthread::mutex> guard(m); m_WorkToDo_mutex.lock(); while(!myThreadData->haveWorkToDo) // check for work to do m_WorkToDo_condvar.wait(m_WorkToDo_mutex); // if no work, wait here myThreadData->haveWorkToDo = false; // need to do this before unlocking the mutex m_WorkToDo_mutex.unlock(); // Do the work switch(myThreadData->typeOfWork) { case e_work: std::cout << "Thread " << threadId << ": Woken with work to do\n"; // Do work myThreadData->workFunc(myThreadData->workData); std::cout << "#Thread " << threadId << ": Work is completed\n"; break; case e_quit: std::cout << "Thread " << threadId << ": Asked to quit\n"; return; // ends the thread } // Now to signal the main thread that my work is completed m_WorkCompleted_mutex.lock(); m_NumOfThreadsDoingWork--; // Unsure if this 'if' would make the program more efficient // if(NumOfThreadsDoingWork == 0) m_WorkCompleted_condvar.notify_one(); // notify the main thread m_WorkCompleted_mutex.unlock(); } } ThreadPool::ThreadPool() { m_numOfThreads = 0; m_NumOfThreadsDoingWork = 0; m_NumOfThreadsGivenJobs = 0; } ThreadPool::~ThreadPool() { if(m_numOfThreads) { DestroyThreadPool(); delete [] m_ThreadData; } } void ThreadPool::CreateThreads(int numOfThreads) { // Check a thread pool has already been created if(m_numOfThreads > 0) return; m_NumOfThreadsGivenJobs = 0; m_NumOfThreadsDoingWork = 0; m_numOfThreads = numOfThreads; m_ThreadData = new ThreadData[m_numOfThreads]; ThreadArgStruct threadArg; for(int i=0; i<m_numOfThreads; ++i) { threadArg.threadId = i; threadArg.threadPoolInstance = this; // Creates the thread and save in a list so we can destroy it later m_ThreadList.push_back( new tthread::thread( ThreadFuncWrapper, (void *)&threadArg ) ); // It takes a little time for a thread to get established. // Best wait until it gets established before creating the next thread. m_ThreadReady_mutex.lock(); while(!m_ThreadData[i].ready) // Check if thread is ready m_ThreadReady_condvar.wait(m_ThreadReady_mutex); // If not, wait here m_ThreadReady_mutex.unlock(); } } // Adds a job to the batch, but doesn't start the job void ThreadPool::SubmitJob(void (*workFunc)(void *), void *workData) { // Check that the thread pool has been created if(!m_numOfThreads) return; if(m_NumOfThreadsGivenJobs >= m_numOfThreads) return; m_ThreadData[m_NumOfThreadsGivenJobs].workFunc = workFunc; m_ThreadData[m_NumOfThreadsGivenJobs].workData = workData; std::cout << "Submitted job " << m_NumOfThreadsGivenJobs << std::endl; m_NumOfThreadsGivenJobs++; } void ThreadPool::StartJobs() { // Check that the thread pool has been created // and some jobs have been assigned if(!m_numOfThreads || !m_NumOfThreadsGivenJobs) return; // Set 'haveworkToDo' flag for all threads m_WorkToDo_mutex.lock(); for(int i=0; i<m_NumOfThreadsGivenJobs; ++i) m_ThreadData[i].haveWorkToDo = true; m_NumOfThreadsDoingWork = m_NumOfThreadsGivenJobs; // Reset this counter so we can resubmit jobs later m_NumOfThreadsGivenJobs = 0; // Notify all threads they have work to do m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); } void ThreadPool::WaitForJobsToComplete() { // Check that a thread pool has been created if(!m_numOfThreads) return; m_WorkCompleted_mutex.lock(); while(m_NumOfThreadsDoingWork > 0) // Check if all threads have completed their work m_WorkCompleted_condvar.wait(m_WorkCompleted_mutex); // If not, wait here m_WorkCompleted_mutex.unlock(); } void ThreadPool::DestroyThreadPool() { std::cout << "Ask threads to quit\n"; m_WorkToDo_mutex.lock(); for(int i=0; i<m_numOfThreads; ++i) { m_ThreadData[i].haveWorkToDo = true; m_ThreadData[i].typeOfWork = e_quit; } m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); // As each thread terminates, catch them here for(int i=0; i<m_numOfThreads; ++i) { tthread::thread *t = m_ThreadList[i]; // Wait for thread to complete t->join(); } m_numOfThreads = 0; } Example of usage: (this calculates pi-squared/6) struct CalculationDataStruct { int inputVal; double outputVal; }; void LongCalculation( void *theSums ) { CalculationDataStruct *sums = (CalculationDataStruct *)theSums; int terms = sums->inputVal; double sum; for(int i=1; i<terms; i++) sum += 1.0/( double(i)*double(i) ); sums->outputVal = sum; } int main(int argc, char** argv) { int numThreads = 10; // Create pool ThreadPool threadPool; threadPool.CreateThreads(numThreads); // Create thread workspace CalculationDataStruct sums[numThreads]; // Set up jobs for(int i=0; i<numThreads; i++) { sums[i].inputVal = 3000*(i+1); threadPool.SubmitJob(LongCalculation, &sums[i]); } // Run the jobs threadPool.StartJobs(); threadPool.WaitForJobsToComplete(); // Print results for(int i=0; i<numThreads; i++) std::cout << "Sum of " << sums[i].inputVal << " terms is " << sums[i].outputVal << std::endl; return 0; } Question: In the ThreadPool::ThreadFunc method, would better performance be obtained if the following if statement if(NumOfThreadsDoingWork == 0) was included? Also, I'd be grateful of criticisms and ways to improve the code. At the same time, I hope the code is of use to others.

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