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• Tomcat stops responding to JK requests

  - by Bruno Reis

  Hello. I have a nasty issue with load-balanced Tomcat servers that are hanging up. Any help would be greatly appreciated. The system I'm running Tomcat 6.0.26 on HotSpot Server 14.3-b01 (Java 1.6.0_17-b04) on three servers sitting behind another server that acts as load balancer. The load balancer runs Apache (2.2.8-1) + MOD_JK (1.2.25). All of the servers are running Ubuntu 8.04. The Tomcat's have 2 connectors configured: an AJP one, and a HTTP one. The AJP is to be used with the load balancer, while the HTTP is used by the dev team to directly connect to a chosen server (if we have a reason to do so). I have Lambda Probe 1.7b installed on the Tomcat servers to help me diagnose and fix the problem soon to be described. The problem Here's the problem: after about 1 day the application servers are up, JK Status Manager starts reporting status ERR for, say, Tomcat2. It will simply get stuck on this state, and the only fix I've found so far is to ssh the box and restart Tomcat. I must also mention that JK Status Manager takes a lot longer to refresh when there's a Tomcat server in this state. Finally, the "Busy" count of the stuck Tomcat on JK Status Manager is always high, and won't go down per se -- I must restart the Tomcat server, wait, then reset the worker on JK. Analysis Since I have 2 connectors on each Tomcat (AJP and HTTP), I still can connect to the application through the HTTP one. The application works just fine like this, very, very fast. That is perfectly normal, since I'm the only one using this server (as JK stopped delegating requests to this Tomcat). To try to better understand the problem, I've taken a thread dump from a Tomcat which is not responding anymore, and from another one that has been restarted recently (say, 1 hour before). The instance that is responding normally to JK shows most of the TP-ProcessorXXX threads in "Runnable" state, with the following stack trace: java.net.SocketInputStream.socketRead0 ( native code ) java.net.SocketInputStream.read ( SocketInputStream.java:129 ) java.io.BufferedInputStream.fill ( BufferedInputStream.java:218 ) java.io.BufferedInputStream.read1 ( BufferedInputStream.java:258 ) java.io.BufferedInputStream.read ( BufferedInputStream.java:317 ) org.apache.jk.common.ChannelSocket.read ( ChannelSocket.java:621 ) org.apache.jk.common.ChannelSocket.receive ( ChannelSocket.java:559 ) org.apache.jk.common.ChannelSocket.processConnection ( ChannelSocket.java:686 ) org.apache.jk.common.ChannelSocket$SocketConnection.runIt ( ChannelSocket.java:891 ) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run ( ThreadPool.java:690 ) java.lang.Thread.run ( Thread.java:619 ) The instance that is stuck show most (all?) of the TP-ProcessorXXX threads in "Waiting" state. These have the following stack trace: java.lang.Object.wait ( native code ) java.lang.Object.wait ( Object.java:485 ) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run ( ThreadPool.java:662 ) java.lang.Thread.run ( Thread.java:619 ) I don't know of the internals of Tomcat, but I would infer that the "Waiting" threads are simply threads sitting on a thread pool. So, if they are threads waiting inside of a thread pool, why wouldn't Tomcat put them to work on processing requests from JK? Solution? So, as I've stated before, the only fix I've found is to stop the Tomcat instance, stop the JK worker, wait the latter's busy count slowly go down, start Tomcat again, and enable the JK worker once again. What is causing this problem? How should I further investigate it? What can I do to solve it? Thanks in advance.

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• Reading email address from contacts fails with weird memory issue - Solved

  - by CapsicumDreams

  Hi all, I'm stumped. I'm trying to get a list of all the email address a person has. I'm using the ABPeoplePickerNavigationController to select the person, which all seems fine. I'm setting my ABRecordRef personDealingWith; from the person argument to - (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person property:(ABPropertyID)property identifier:(ABMultiValueIdentifier)identifier { and everything seems fine up till this point. The first time the following code executes, all is well. When subsequently run, I can get issues. First, the code: // following line seems to make the difference (issue 1) // NSLog(@"%d", ABMultiValueGetCount(ABRecordCopyValue(personDealingWith, kABPersonEmailProperty))); // construct array of emails ABMultiValueRef multi = ABRecordCopyValue(personDealingWith, kABPersonEmailProperty); CFIndex emailCount = ABMultiValueGetCount(multi); if (emailCount > 0) { // collect all emails in array for (CFIndex i = 0; i < emailCount; i++) { CFStringRef emailRef = ABMultiValueCopyValueAtIndex(multi, i); [emailArray addObject:(NSString *)emailRef]; CFRelease(emailRef); } } // following line also matters (issue 2) CFRelease(multi); If compiled as written, the are no errors or static analysis problems. This crashes with a *** -[Not A Type retain]: message sent to deallocated instance 0x4e9dc60 error. But wait, there's more! I can fix it in either of two ways. Firstly, I can uncomment the NSLog at the top of the function. I get a leak from the NSLog's ABRecordCopyValue every time through, but the code seems to run fine. Also, I can comment out the CFRelease(multi); at the end, which does exactly the same thing. Static compilation errors, but running code. So without a leak, this function crashes. To prevent a crash, I need to haemorrhage memory. Neither is a great solution. Can anyone point out what's going on? Solution: It turned out that I wasn't storing the ABRecordRef personDealingWith var correctly. I'm still not sure how to do that properly, but instead of having the functionality in another routine (performed later), I'm now doing the grunt-work in the delegate method, and using the derived results at my leisure. The new (working) routine: - (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person { // as soon as they select someone, return personDealingWithFullName = (NSString *)ABRecordCopyCompositeName(person); personDealingWithFirstName = (NSString *)ABRecordCopyValue(person, kABPersonFirstNameProperty); // construct array of emails [personDealingWithEmails removeAllObjects]; ABMutableMultiValueRef multi = ABRecordCopyValue(person, kABPersonEmailProperty); if (ABMultiValueGetCount(multi) > 0) { // collect all emails in array for (CFIndex i = 0; i < ABMultiValueGetCount(multi); i++) { CFStringRef emailRef = ABMultiValueCopyValueAtIndex(multi, i); [personDealingWithEmails addObject:(NSString *)emailRef]; CFRelease(emailRef); } } CFRelease(multi); return NO; }

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• Postmortem debugging with WinDBG.

  - by Drazar

  I have an WCF-service running on an server, and occasionally(1-2 times every month) it throws an COMException with the informative message ”Unknown error (0x8005008)”. When i googled for this particular error I only got threads about problems when creating virtual directories in IIS. And the source code hasn’t anything with making a virtual directory in IIS. DirectoryServiceLib.LdapProvider.Directory - CreatePost - Could not create employee for 195001010000,000000000000: System.Runtime.InteropServices.COMException (0x80005008): Unknown error (0x80005008) at System.DirectoryServices.PropertyValueCollection.PopulateList I've taken a memorydump when I catch the Exception for further analysis in WinDBG. After switching to the right thread I executed the !CLRStack command: 000000001b8ab6d8 000000007708671a [NDirectMethodFrameStandalone: 000000001b8ab6d8] Common.MemoryDump.MiniDumpWriteDump(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr) 000000001b8ab680 000007ff002808d8 DomainBoundILStubClass.IL_STUB_PInvoke(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr) 000000001b8ab780 000007ff00280812 Common.MemoryDump.CreateMiniDump(System.String) 000000001b8ab7e0 000007ff0027b218 DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8ad6d8 000007fef8816869 [HelperMethodFrame: 000000001b8ad6d8] 000000001b8ad820 000007feec2b6c6f System.DirectoryServices.PropertyValueCollection.PopulateList() 000000001b8ad860 000007feec225f0f System.DirectoryServices.PropertyValueCollection..ctor(System.DirectoryServices.DirectoryEntry, System.String) 000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String) 000000001b8ad8f0 000007ff00274d34 Common.DirectoryEntryExtension.GetStringAttribute(System.String) 000000001b8ad940 000007ff0027f507 DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost) 000000001b8ad980 000007ff0027a7cf DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8adbe0 000007ff00279532 DirectoryServiceLib.WCFDirectory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8adc60 000007ff001f47bd DynamicClass.SyncInvokeCreatePost(System.Object, System.Object[], System.Object[]) My conclusion is that it fails when the code is calling System.DirectoryServices.PropertyCollection.get_Item(System.String). So after issuing an !CLRStack -a I get this result: 000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String) PARAMETERS: this = <no data> propertyName = <no data> LOCALS: <CLR reg> = 0x0000000001dcef78 <no data> My very first question is why does it display no data on the propertyname? I am kinda new on Windbg. However I executed an dumpobject on = 0x0000000001dcef78: 0:013> !do 0x0000000001dcef78 Name: System.String MethodTable: 000007fef66d6960 EEClass: 000007fef625eec8 Size: 74(0x4a) bytes File: C:\Windows\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll String: personalprescriptioncode Fields: MT Field Offset Type VT Attr Value Name 000007fef66dc848 40000ed 8 System.Int32 1 instance 24 m_stringLength 000007fef66db388 40000ee c System.Char 1 instance 70 m_firstChar 000007fef66d6960 40000ef 10 System.String 0 shared static Empty >> Domain:Value 0000000000174e10:00000000019d1420 000000001a886f50:00000000019d1420 << So when the source code wants to fetch the personalprescriptioncode from Active Directory(what is used for persistence layer) it fails. Looking back at the stack it is when issuing the Copy method. DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost) So looking in the sourcecode: DirectoryPost postInLimbo = DirectoryPostFactory.Instance().GetDirectoryPost(LdapConfigReader.Instance().GetConfigValue("LimboDN"), idGenPerson.ID.UserId); if (postInLimbo != null) newPost.Copy(postInLimbo); This code is looking for another post in OU=limbo with the same UserId and if it finds one it copies the attributes to the new post. In this case it does and it fails with personalprescriptioncode. I've looked in Active Directory under OU=Limbo and the post exist there with the attribute personalprescriptioncode=31243. Question 1: Why does it display no data for some of the PARAMETERS and LOCALS? Is it the GC who has cleaned up before the memorydump had been created. Question 2: Is there anymore i can do to get to the solution to this problem?

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• Thread Synchronisation 101

  - by taspeotis

  Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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• In Ruby, how to I read memory values from an external process?

  - by grg-n-sox

  So all I simply want to do is make a Ruby program that reads some values from known memory address in another process's virtual memory. Through my research and basic knowledge of hex editing a running process's x86 assembly in memory, I have found the base address and offsets for the values in memory I want. I do not want to change them; I just want to read them. I asked a developer of a memory editor how to approach this abstract of language and assuming a Windows platform. He told me the Win32API calls for OpenProcess, CreateProcess, ReadProcessMemory, and WriteProcessMemory were the way to go using either C or C++. I think that the way to go would be just using the Win32API class and mapping two instances of it; One for either OpenProcess or CreateProcess, depending on if the user already has th process running or not, and another instance will be mapped to ReadProcessMemory. I probably still need to find the function for getting the list of running processes so I know which running process is the one I want if it is running already. This would take some work to put all together, but I am figuring it wouldn't be too bad to code up. It is just a new area of programming for me since I have never worked this low level from a high level language (well, higher level than C anyways). I am just wondering of the ways to approach this. I could just use a bunch or Win32API calls, but that means having to deal with a bunch of string and array pack and unpacking that is system dependant I want to eventually make this work cross-platform since the process I am reading from is produced from an executable that has multiple platform builds, (I know the memory address changes from system to system. The idea is to have a flat file that contains all memory mappings so the Ruby program can just match the current platform environment to the matching memory mapping.) but from the looks of things I'll just have to make a class that wraps whatever is the current platform's system shared library memory related function calls. For all I know, there could already exist a Ruby gem that takes care of all of this for me that I am just not finding. I could also possibly try editing the executables for each build to make it so whenever the memory values I want to read from are written to by the process, it also writes a copy of the new value to a space in shared memory that I somehow have Ruby make an instance of a class that is a pointer under the hood to that shared memory address and somehow signal to the Ruby program that the value was updated and should be reloaded. Basically a interrupt based system would be nice, but since the purpose of reading these values is just to send to a scoreboard broadcasted from a central server, I could just stick to a polling based system that sends updates at fixed time intervals. I also could just abandon Ruby altogether and go for C or C++ but I do not know those nearly as well. I actually know more x86 than C++ and I only know C as far as system independent ANSI C and have never dealt with shared system libraries before. So is there a gem or lesser known module available that has already done this? If not, then any additional information as to how to accomplish this would be nice. I guess, long story short, how do I do all this? Thanks in advance, Grg PS: Also a confirmation that those Win32API calls should be aimed at the kernel32.dll library would be nice.

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• Java thread dump where main thread has no call stack? (jsvc)

  - by dwhsix

  We have a java process running as a daemon (under jsvc). Every several days it just stops doing any work; output to the logfile stops (it is pretty verbose, on 5-minute intervals) and it consumes no CPU or IO. There are no exceptions logged in the logfile nor in syserr or sysout. The last log statement is just prior to a db commit being done, but there is no open connection on the db server (MySQL) and reviewing the code, there should always be additional log output after that, even if it had encountered an exception that was going to bubble up. The most curious thing I find is that in the thread dump (included below), there's no thread in our code at all, and the main thread seems to have no context whatsoever: "main" prio=10 tid=0x0000000000614000 nid=0x445d runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE As noted earlier, this is a daemon process running using jsvc, but I don't know if that has anything to do with it (I can restructure the code to also allow running it directly, to test). Any suggestions on what might be happening here? Thanks... dwh Full thread dump: Full thread dump Java HotSpot(TM) 64-Bit Server VM (14.2-b01 mixed mode): "MySQL Statement Cancellation Timer" daemon prio=10 tid=0x00002aaaf81b8800 nid=0x447b in Object.wait() [0x00002aaaf6a22000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x00002aaab5556d50> (a java.util.TaskQueue) at java.lang.Object.wait(Object.java:485) at java.util.TimerThread.mainLoop(Timer.java:483) - locked <0x00002aaab5556d50> (a java.util.TaskQueue) at java.util.TimerThread.run(Timer.java:462) "Low Memory Detector" daemon prio=10 tid=0x00000000006a4000 nid=0x4479 runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE "CompilerThread1" daemon prio=10 tid=0x00000000006a1000 nid=0x4477 waiting on condition [0x0000000000000000] java.lang.Thread.State: RUNNABLE "CompilerThread0" daemon prio=10 tid=0x000000000069d000 nid=0x4476 waiting on condition [0x0000000000000000] java.lang.Thread.State: RUNNABLE "Signal Dispatcher" daemon prio=10 tid=0x000000000069b000 nid=0x4465 waiting on condition [0x0000000000000000] java.lang.Thread.State: RUNNABLE "Finalizer" daemon prio=10 tid=0x0000000000678800 nid=0x4464 in Object.wait() [0x00002aaaf61d6000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x00002aaab54a1cb8> (a java.lang.ref.ReferenceQueue$Lock) at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:118) - locked <0x00002aaab54a1cb8> (a java.lang.ref.ReferenceQueue$Lock) at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:134) at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159) "Reference Handler" daemon prio=10 tid=0x0000000000676800 nid=0x4463 in Object.wait() [0x00002aaaf60d5000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x00002aaab54a1cf0> (a java.lang.ref.Reference$Lock) at java.lang.Object.wait(Object.java:485) at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116) - locked <0x00002aaab54a1cf0> (a java.lang.ref.Reference$Lock) "main" prio=10 tid=0x0000000000614000 nid=0x445d runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE "VM Thread" prio=10 tid=0x0000000000670000 nid=0x4462 runnable "GC task thread#0 (ParallelGC)" prio=10 tid=0x000000000061e000 nid=0x445e runnable "GC task thread#1 (ParallelGC)" prio=10 tid=0x0000000000620000 nid=0x445f runnable "GC task thread#2 (ParallelGC)" prio=10 tid=0x0000000000622000 nid=0x4460 runnable "GC task thread#3 (ParallelGC)" prio=10 tid=0x0000000000623800 nid=0x4461 runnable "VM Periodic Task Thread" prio=10 tid=0x00000000006a6800 nid=0x447a waiting on condition JNI global references: 797 Heap PSYoungGen total 162944K, used 48388K [0x00002aaadff40000, 0x00002aaaf2ab0000, 0x00002aaaf5490000) eden space 102784K, 47% used [0x00002aaadff40000,0x00002aaae2e81170,0x00002aaae63a0000) from space 60160K, 0% used [0x00002aaaeb850000,0x00002aaaeb850000,0x00002aaaef310000) to space 86720K, 0% used [0x00002aaae63a0000,0x00002aaae63a0000,0x00002aaaeb850000) PSOldGen total 699072K, used 699072K [0x00002aaab5490000, 0x00002aaadff40000, 0x00002aaadff40000) object space 699072K, 100% used [0x00002aaab5490000,0x00002aaadff40000,0x00002aaadff40000) PSPermGen total 21248K, used 9252K [0x00002aaab0090000, 0x00002aaab1550000, 0x00002aaab5490000) object space 21248K, 43% used [0x00002aaab0090000,0x00002aaab09993e8,0x00002aaab1550000)

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• C program runs in Cygwin but not Linux (Malloc)

  - by Shawn

  I have a heap allocation error that I cant spot in my code that is picked up on vanguard/gdb on Linux but runs perfectly on a Windows cygwin environment. I understand that Linux could be tighter with its heap allocation than Windows but I would really like to have a response that discovers the issue/possible fix. I'm also aware that I shouldn't typecast malloc in C but it's a force of habit and doesn't change my problem from happening. My program actually compiles without error on both Linux & Windows but when I run it in Linux I get a scary looking result: malloc.c:3074: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)-bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) = (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)-size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed. Aborted Attached snippet from my code that is being pointed to as the error for review: /* Main */ int main(int argc, char * argv[]) { FILE *pFile; unsigned char *buffer; long int lSize; pFile = fopen ( argv[1] , "r" ); if (pFile==NULL) {fputs ("File error on arg[1]",stderr); return 1;} fseek (pFile , 0 , SEEK_END); lSize = ftell (pFile); rewind (pFile); buffer = (char*) malloc(sizeof(char) * lSize+1); if (buffer == NULL) {fputs ("Memory error",stderr); return 2;} bitpair * ppairs = (bitpair *) malloc(sizeof(bitpair) * (lSize+1)); //line 51 below calcpair(ppairs, (lSize+1)); /* irrelevant stuff */ fclose(pFile); free(buffer); free(ppairs); } typedef struct { long unsigned int a; //not actual variable names... Yes I need them to be long unsigned long unsigned int b; long unsigned int c; long unsigned int d; long unsigned int e; } bitpair; void calcpair(bitpair * ppairs, long int bits); void calcPairs(bitpair * ppairs, long int bits) { long int i, top, bot, var_1, var_2; int count = 0; for(i = 0; i < cs; i++) { top = 0; ppairs[top].e = 1; do { bot = count; count++; } while(ppairs[bot].e != 0); ppairs[bot].e = 1; var_1 = bot; var_2 = top; calcpair * bp = &ppairs[var_2]; bp->a = var_2; bp->b = var_1; bp->c = i; bp = &ppairs[var_1]; bp->a = var_2; bp->b = var_1; bp->c = i; } return; } gdb reports: free(): invalid pointer: 0x0000000000603290 * valgrind reports the following message 5 times before exiting due to "VALGRIND INTERNAL ERROR" signal 11 (SIGSEGV): Invalid read of size 8 ==2727== at 0x401043: calcPairs (in /home/user/Documents/5-3/ubuntu test/main) ==2727== by 0x400C9A: main (main.c:51) ==2727== Address 0x5a607a0 is not stack'd, malloc'd or (recently) free'd

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• Segmentation fault in Qt Designer 4.6 with custom widget

  - by chedi

  Hi, I had a segmentation fault when using my new Qt Widget with Qt Designer 4.6. The problem arise when trying to preview the new widget. when using gdb I found that the problem is in qdesigner_internal::WidgetFactory::applyStyleToTopLevel: Program received signal SIGSEGV, Segmentation fault. qdesigner_internal::WidgetFactory::applyStyleToTopLevel (style=0x0, widget=0x1829df0) at /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/widgetfactory.cpp:777 777 /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/widgetfactory.cpp: No such file or directory. in /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/widgetfactory.cpp (gdb) bt #0 qdesigner_internal::WidgetFactory::applyStyleToTopLevel (style=0x0, widget=0x1829df0) at /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/widgetfactory.cpp:777 #1 0x00007ffff7475bed in qdesigner_internal::QDesignerFormBuilder::createPreview (fw=, styleName=..., appStyleSheet=..., deviceProfile=, scriptErrors= 0x7fffffffbee0, errorMessage=0x7fffffffc3f0) at /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/qdesigner_formbuilder.cpp:404 #2 0x00007ffff7476773 in qdesigner_internal::QDesignerFormBuilder::createPreview (fw=0x0, styleName=..., appStyleSheet=..., deviceProfile=..., errorMessage=0x0) at /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/qdesigner_formbuilder.cpp:439 #3 0x00007ffff7532b27 in qdesigner_internal::PreviewManager::createPreview (this=0x837f20, fw=0x1879200, pc=..., deviceProfileIndex=-1, errorMessage=0x7fffffffc3f0, initialZoom=-1) at /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/previewmanager.cpp:686 #4 0x00007ffff75343cf in qdesigner_internal::PreviewManager::showPreview (this=0x837f20, fw=0x1879200, pc=..., deviceProfileIndex=-1, errorMessage=0x7fffffffc3f0) at /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/previewmanager.cpp:760 #5 0x00007ffff753472f in qdesigner_internal::PreviewManager::showPreview (this=0x837f20, fw=0x1879200, style=..., deviceProfileIndex=-1, errorMessage=0x7fffffffc3f0) at /var/tmp/qt-x11-src-4.6.0/tools/designer/src/lib/shared/previewmanager.cpp:659 because a null pointer was passed there: void WidgetFactory::applyStyleToTopLevel(QStyle *style, QWidget *widget) { const QPalette standardPalette = style-standardPalette(); if (widget-style() == style && widget-palette() == standardPalette) return; //.... } I'm new in Qt and this is my first custom widget. does anybody have a clue for solving this. here is my widget code MBICInput::MBICInput(QWidget *parent) : QStackedWidget(parent){ displayPage = new QWidget(); displayPage-setObjectName(QString::fromUtf8("displayPage")); inputLB = new QLabel(displayPage); inputLB-setObjectName(QString::fromUtf8("inputLabel")); inputLB-setCursor(QCursor(Qt::PointingHandCursor)); addWidget(displayPage); EditPage = new QWidget(); EditPage-setProperty("EditInputLine", QVariant(true)); EditPage-setObjectName(QString::fromUtf8("EditPage")); inputInput = new QLineEdit(EditPage); inputInput-setGeometry(QRect(5, 10, 231, 25)); inputInput-setObjectName(QString::fromUtf8("input")); addWidget(EditPage); _animation = new QString(""); _message = new QString("Message"); _validator = new QRegExpValidator(QRegExp("[a-zA-Z]+"), this); } MBICInput::~MBICInput() { } QValidator::State MBICInput::validate(QString &text, int &pos) const{ return _validator-validate(text, pos); } void MBICInput::paintEvent(QPaintEvent *) { QPainter painter(this); painter.setRenderHint(QPainter::Antialiasing); } QSize MBICInput::minimumSizeHint() const{ return QSize(200, 40); } QSize MBICInput::sizeHint() const{ return QSize(200, 40); } void MBICInput::setAnimation(const QString &animation){ *_animation = animation; update(); } QString MBICInput::animation() const{ return *_animation; } void MBICInput::setMessage(const QString &message){ *_message = message; update(); } QString MBICInput::message() const{ return *_message; } void MBICInput::mousePressEvent(QMouseEvent *event){ if(currentIndex()==0){ setCurrentIndex(1); }else{ setCurrentIndex(0); } update(); }

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• Error Handling without Exceptions

  - by James

  While searching SO for approaches to error handling related to business rule validation , all I encounter are examples of structured exception handling. MSDN and many other reputable development resources are very clear that exceptions are not to be used to handle routine error cases. They are only to be used for exceptional circumstances and unexpected errors that may occur from improper use by the programmer (but not the user.) In many cases, user errors such as fields that are left blank are common, and things which our program should expect, and therefore are not exceptional and not candidates for use of exceptions. QUOTE: Remember that the use of the term exception in programming has to do with the thinking that an exception should represent an exceptional condition. Exceptional conditions, by their very nature, do not normally occur; so your code should not throw exceptions as part of its everyday operations. Do not throw exceptions to signal commonly occurring events. Consider using alternate methods to communicate to a caller the occurrence of those events and leave the exception throwing for when something truly out of the ordinary happens. For example, proper use: private void DoSomething(string requiredParameter) { if (requiredParameter == null) throw new ArgumentExpcetion("requiredParameter cannot be null"); // Remainder of method body... } Improper use: // Renames item to a name supplied by the user. Name must begin with an "F". public void RenameItem(string newName) { // Items must have names that begin with "F" if (!newName.StartsWith("F")) throw new RenameException("New name must begin with /"F/""); // Remainder of method body... } In the above case, according to best practices, it would have been better to pass the error up to the UI without involving/requiring .NET's exception handling mechanisms. Using the same example above, suppose one were to need to enforce a set of naming rules against items. What approach would be best? Having the method return a enumerated result? RenameResult.Success, RenameResult.TooShort, RenameResult.TooLong, RenameResult.InvalidCharacters, etc. Using an event in a controller class to report to the UI class? The UI calls the controller's RenameItem method, and then handles an AfterRename event that the controller raises and that has rename status as part of the event args? The controlling class directly references and calls a method from the UI class that handles the error, e.g. ReportError(string text). Something else... ? Essentially, I want to know how to perform complex validation in classes that may not be the Form class itself, and pass the errors back to the Form class for display -- but I do not want to involve exception handling where it should not be used (even though it seems much easier!) Based on responses to the question, I feel that I'll have to state the problem in terms that are more concrete: UI = User Interface, BLL = Business Logic Layer (in this case, just a different class) User enters value within UI. UI reports value to BLL. BLL performs routine validation of the value. BLL discovers rule violation. BLL returns rule violation to UI. UI recieves return from BLL and reports error to user. Since it is routine for a user to enter invalid values, exceptions should not be used. What is the right way to do this without exceptions?

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• iPhone Memory Error - when using Build & Debug, How to debug?

  - by LonH99

  I'm a newbie and need some help with an iPhone App running on the Simulator. The app works fine running with Build & Run or Build & Run - breakpoints off, but blows when running with Build & Debug - Breakpoints on. Any help or thoughts would be greatly appreciated. Lon Specifics: No breakpoints set, never gets to any visible simulator results, seems to blow during initialization phase before it can generate any output. Source of app is the DrinkMixer example, in the "Head First iPhone development" book (example built up to page 280) by Dan & Tracey Pilone. Blows With this Error Message: Attaching to process 970. Pending breakpoint 1 - "*0x01c1b001" resolved Program received signal: “EXC_BAD_ACCESS”. No memory available to program now: unsafe to call malloc Data Formatters temporarily unavailable, will re-try after a 'continue'. (Not safe to call dlopen at this time.) No memory available to program now: unsafe to call malloc --- Leaks: The only object noted as "leaked Object" is: Leaked Object # Address Size Responsible Library Responsible Frame Malloc 128 Bytes <blank> 0x3c11950 128Bytes CoreGraphics open_handle_to_dylib_path ___ Object Allocations shows (Highest at top = CFString): Category --- Overall Bytes -- #Overall -- Live Bytes -- #Living * All Allocations * 497kb #5888 496kb #5878 10 CFString 42kb #1126 42kb Malloc 32.00 KB 32kb #1 32kb Malloc 1.00 KB 29kb #29 29kb Malloc 8.00 KB 24kb #3 24kb Malloc 32 Bytes 20.81kb #666 20.75kb Malloc 1.50 KB 19.5kb #13 19.5kb CFDictionary (key-store) 17.64kb #159 17.64kb (note: Except for "All Allocations, the #Living is the same as #Overall) --- List of Calls from Debugger: #0 0x01c1b010 in CFStringCreateByCombiningStrings #1 0x023a0779 in LoadFontPathCache #2 0x023a096b in Initialize #3 0x023a0f3e in GSFontCreateWithName #4 0x003d4575 in +[UIFont boldSystemFontOfSize:] #5 0x002cddaa in +[UINavigationButton defaultFont] #6 0x002d9e37 in -[UINavigationButton initWithValue:width:style:barStyle:possibleTitles:tintColor:] #7 0x002cdc75 in -[UINavigationButton initWithImage:width:style:] #8 0x00468eeb in -[UIBarButtonItem(Static) createViewForNavigationItem:] #9 0x002d1b56 in -[UINavigationItem customRightView] #10 0x002d20e3 in -[UINavigationItem updateNavigationBarButtonsAnimated:] #11 0x002d1e1a in -[UINavigationItem setRightBarButtonItem:] #12 0x00002e7b in -[RootViewController viewDidLoad] at RootViewController.m:41 #13 0x00313796 in -[UIViewController view] #14 0x00311d92 in -[UIViewController contentScrollView] #15 0x0031c2b4 in -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] #16 0x0031b32e in -[UINavigationController _layoutViewController:] #17 0x0031cd1a in -[UINavigationController _startTransition:fromViewController:toViewController:] #18 0x0031831a in -[UINavigationController _startDeferredTransitionIfNeeded] #19 0x004362e4 in -[UILayoutContainerView layoutSubviews] #20 0x035342b0 in -[CALayer layoutSublayers] #21 0x0353406f in CALayerLayoutIfNeeded #22 0x035338c6 in CA::Context::commit_transaction #23 0x0353353a in CA::Transaction::commit #24 0x00295ef9 in -[UIApplication _reportAppLaunchFinished] #25 0x0029bb88 in -[UIApplication handleEvent:withNewEvent:] #26 0x002976d3 in -[UIApplication sendEvent:] #27 0x0029e0b5 in _UIApplicationHandleEvent #28 0x023a3ed1 in PurpleEventCallback #29 0x01bb6b80 in CFRunLoopRunSpecific #30 0x01bb5c48 in CFRunLoopRunInMode #31 0x00295e69 in -[UIApplication _run] #32 0x0029f003 in UIApplicationMain #33 0x00002ba0 in main at main.m:14 The code, including line #41 (noted below) is as follows. And thanks for the formatting help and comment: import "RootViewController.h" import "DrinkDetailViewController.h"; import "DrinkConstants.h" import "AddDrinkViewController.h" @implementation RootViewController @synthesize drinks, addButtonItem; - (void)viewDidLoad { [super viewDidLoad]; // add PATH for PLIST NSString *path = [[NSBundle mainBundle] pathForResource: @"DrinkDirections" ofType:@"plist"]; NSMutableArray *tmpArray = [[NSMutableArray alloc] initWithContentsOfFile:path]; self.drinks = tmpArray; [tmpArray release]; // Next is Line #41 - I removed earlier empty lines & Comments self.navigationItem.rightBarButtonItem = self.addButtonItem; } - (IBAction) addButtonPressed: (id) sender { NSLog(@"Add button pressed!");

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• Qt - reloading widget contents

  - by bullettime

  I'm trying to modify the fridge magnets example by adding a button that will reload the widget where the draggable labels are drawn, reflecting any changes made to the text file it reads. I defined another class that would contain the button and the DragWidget object, so there would be an instance of this class instead of DragWidget in main(): class wrapWidget: public QWidget { public: wrapWidget(); }; wrapWidget::wrapWidget() { QGridLayout *gridlayout = new QGridLayout(); DragWidget *w = new DragWidget(); QPushButton *b = new QPushButton("refresh"); gridlayout ->addWidget(w,0,0); gridlayout ->addWidget(b,1,0); setLayout(gridlayout ); connect(b,SIGNAL(clicked()),w,SLOT(draw())); } The call to connect is where I'm trying to do the refresh thing. In the original fridge magnets example, all the label drawing code was inside the constructor of the DragWidget class. I moved that code to a public method that I named 'draw()', and called this method from the constructor instead. Here's DragWidget definition and implementation: #include <QWidget> QT_BEGIN_NAMESPACE class QDragEnterEvent; class QDropEvent; QT_END_NAMESPACE class DragWidget : public QWidget { public: DragWidget(QWidget *parent = 0); public slots: void draw(); protected: void dragEnterEvent(QDragEnterEvent *event); void dragMoveEvent(QDragMoveEvent *event); void dropEvent(QDropEvent *event); void mousePressEvent(QMouseEvent *event); void paintEvent(QPaintEvent *event); }; DragWidget::DragWidget(QWidget *parent) : QWidget(parent) { draw(); QPalette newPalette = palette(); newPalette.setColor(QPalette::Window, Qt::white); setPalette(newPalette); setMinimumSize(400, 100);//qMax(200, y)); setWindowTitle(tr("Fridge Magnets")); setAcceptDrops(true); } void DragWidget::draw(){ QFile dictionaryFile(":/dictionary/words.txt"); dictionaryFile.open(QFile::ReadOnly); QTextStream inputStream(&dictionaryFile); int x = 5; int y = 5; while (!inputStream.atEnd()) { QString word; inputStream >> word; if (!word.isEmpty()) { DragLabel *wordLabel = new DragLabel(word, this); wordLabel->move(x, y); wordLabel->show(); wordLabel->setAttribute(Qt::WA_DeleteOnClose); x += wordLabel->width() + 2; if (x >= 245) { x = 5; y += wordLabel->height() + 2; } } } } I thought that maybe calling draw() as a slot would be enough to reload the labels, but it didn't work. Putting the draw() call inside the widget's overriden paintEvent() instead of the constructor didn't work out as well, the program would end up in an infinite loop. What I did was obviously not the right way of doing it, so what should I be doing instead?

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• How to structure a Kohana MVC application with dynamically added fields and provide validation and f

  - by Matt H

  I've got a bit of a problem. I have a Kohana application that has dynamically added fields. The fields that are added are called DISA numbers. In the model I look these up and the result is returned as an array. I encode the array into a JSON string and use JQuery to populate them The View knows the length of the array and so creates as many DISA elements as required before display. See the code below for a summary of how that works. What I'm finding is that this is starting to get difficult to manage. The code is becoming messy. Error handling of this type of dynamic content is ending up being spread all over the place. Not only that, it doesn't work how I want. What you see here is just a small snippet of code. For error handling I am using the validation library. I started by using add_rules on all the fields that come back in the post. As they are always phone numbers I set a required rule (when it's there) and a digit rule on the validation-as_array() keys. That works. The difficulty is actually giving it back to the view. i.e. dynamically added javascript field. Submits back to form. Save contents into a session. View has to load up fields from database + those from the previous post and signal the fields that have problems. It's all quite messy and I'm getting this code spread through both the view the controller and the model. So my question is. Have you done this before in Kohana and how have you handled it? There must be an easier way right? Code snippet. -- edit.php -- public function phone($id){ ... $this->template->content->disa_numbers = $phones->fetch_disa_numbers($this->account, $id); ... } -- phones.php -- public function fetch_disa_numbers($account, $id) { $query = $this->db->query("SELECT id, cid_in FROM disa WHERE owner_ext=?", array($id)); if (!$query){ return ''; } return $query; } -- edit_phones.php --- <script type="text/javascript"> var disaId = 1; function delDisaNumber(element){ /* Put 'X_' on the front of the element name to mark this for deletion */ $(element).prev().attr('name', 'X_'+$(element).prev().attr('name')); $(element).parent().hide(); } function addDisaNumber(){ /* input name is prepended with 'N_' which means new */ $("#disa_numbers").append("<li><input name='N_disa"+disaId+"' id='disa'"+ "type='text'/><a class='hide' onClick='delDisaNumber(this)'></a></li>"); disaId++; } </script> ... <php echo form::open("edit/saveDisaNumbers/".$phone, array("class"=>"section", "id"=>"disa_form")); echo form::open_fieldset(array("class"=>"balanced-grid")); ?> <ul class="fields" id="disa_numbers"> <?php $disaId = 1; foreach ( $disa_numbers as $disa_number ){ echo '<li>'; echo form::input('disa'.$disaId, $disa_number->cid_in); echo'<a class="hide" onclick="delDisaNumber(this)"></a>'; echo "</li>"; $disaId++; } ?> </ul> <button type="button"onclick="addDisaNumber()"><a class="add"></a>Add number</button> <?php echo form::submit('submit', 'Save'); echo form::close(); ?>

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• How to save data from multiple views of an iPhone app?

  - by DownUnder

  Hi Everyone. I'm making an app where I need to save the text in multiple views in the app when the app quits. I also need to be able to remove all of the data from just one of those views and when the app quits, it's possible not all of those views will have been created yet. After reading this post I thought perhaps it would be good to use a singleton that manages my app data which loads in the data when it is first requested and saved it when the app quits. Then in each view where I need to save data I can just set it on the singleton. I gave it a go but have run into some issues. At first I didn't synthesize the properties (as in the post I was using as a guide) but the compiler told me I needed to make getters and setters, so I did. Now when my applicationWIllTerminate: gets call the app crashes and the console says "Program received signal: “EXC_BAD_ACCESS”. kill quit". Is anyone able to tell me what I'm doing wrong, or suggest a better approach to saving the data? //SavedData.h #import <Foundation/Foundation.h> #define kFileName @"appData.plist" @interface SavedData : NSObject { NSString *information; NSString *name; NSString *email; NSString *phone; NSString *mobile; } @property(assign) NSString *information; @property(assign) NSString *name; @property(assign) NSString *email; @property(assign) NSString *phone; @property(assign) NSString *mobile; + (SavedData *)singleton; + (NSString *)dataFilePath; + (void)applicationWillTerminate:(NSNotification *)notification; @end //SavedData.m #import "SavedData.h" @implementation SavedData @synthesize information; @synthesize name; @synthesize email; @synthesize phone; @synthesize mobile; static SavedData * SavedData_Singleton = nil; + (SavedData *)singleton{ if (nil == SavedData_Singleton){ SavedData_Singleton = [[SavedData_Singleton alloc] init]; NSString *filePath = [self dataFilePath]; if([[NSFileManager defaultManager] fileExistsAtPath:filePath]){ NSMutableArray * array = [[NSMutableArray alloc] initWithContentsOfFile:filePath]; information = [array objectAtIndex:0]; name = [array objectAtIndex:1]; email = [array objectAtIndex:2]; phone = [array objectAtIndex:3]; mobile = [array objectAtIndex:4]; [array release]; } UIApplication *app = [UIApplication sharedApplication]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillTerminate:) name:UIApplicationWillTerminateNotification object:app]; } return SavedData_Singleton; } + (NSString *)dataFilePath{ NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *DocumentsDirectory = [paths objectAtIndex:0]; return [DocumentsDirectory stringByAppendingPathComponent:kFileName]; } + (void)applicationWillTerminate:(NSNotification *)notification{ NSLog(@"Application will terminate received"); NSMutableArray *array = [[NSMutableArray alloc] init]; [array addObject:information]; [array addObject:name]; [array addObject:email]; [array addObject:phone]; [array addObject:mobile]; [array writeToFile:[self dataFilePath] atomically:YES]; [array release]; } @end Then when I want to use it I do myLabel.text = [SavedData singleton].information; And when I change the field [SavedData singleton].information = @"my string"; Any help will be very much appreciated!

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• Socket in C: recv overwrite a char[]

  - by Possa

  Hi all, I'm trying to make a little client-server script like many others that I've done in the past. But in this one I have a problem. It is better if I post the code and the output it give me. Code: #include <mysql.h> //not important now #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <signal.h> #include <string.h> //constant definition #define SERVER_PORT 2121 #define LINESIZE 21 //global var definition char victim_ip[LINESIZE], file_write[LINESIZE], hacker_ip[LINESIZE]; //function void leggi (int); //not use now for debugging purpose //void scriviDB (); //not important now main () { int sock, client_len, fd; struct sockaddr_in server, client; // transport end point if((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) { perror("system call socket fail"); exit(1); } server.sin_family = AF_INET; server.sin_addr.s_addr = inet_addr("10.10.10.1"); server.sin_port = htons(SERVER_PORT); // binding address at transport end point if (bind(sock, (struct sockaddr *)&server, sizeof server) == -1) { perror("system call bind fail"); exit(1); } //fprintf(stderr, "Server open: listening.\n"); listen(sock, 5); /* managae client connection */ while (1) { client_len = sizeof(client); if ((fd = accept(sock, (struct sockaddr *)&client, &client_len)) < 0) { perror("accepting connection"); exit(1); } strcpy(hacker_ip, inet_ntoa(client.sin_addr)); printf("1 %s\n", hacker_ip); //debugging purpose //leggi(fd); ////////////////////////// //receive client recv(fd, victim_ip, LINESIZE, 0); victim_ip[sizeof(victim_ip)] = '\0'; printf("2 %s\n", hacker_ip); //debugging purpose recv(fd, file_write, LINESIZE, 0); file_write[sizeof(file_write)] = '\0'; printf("3 %s\n", hacker_ip); //debugging purpose printf("%s@%s for %s\n", file_write, victim_ip, hacker_ip); //send to client send(fd, hacker_ip, 40, 0); //now is hacker_ip for debug ///////////////////////// close(fd); }//end while exit(0); } //end main Client send string: ./send -i 10.10.10.4 -f filename.ext so the script send -i (IP) and -f (FILE) at the server. Here's my output server side: 1 10.10.10.6 2 10.10.10.6 3 [email protected] for As you can see the printf(3) and the printf(ip,file,ip) fail. I don't know how and where but someone overwrite my hacker_ip string. Thanks for your help! :)

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• Help with infrequent segmentation fault in accessing boost::unordered_multimap or struct

  - by Sarah

  I'm having trouble debugging a segmentation fault. I'd appreciate tips on how to go about narrowing in on the problem. The error appears when an iterator tries to access an element of a struct Infection, defined as: struct Infection { public: explicit Infection( double it, double rt ) : infT( it ), recT( rt ) {} double infT; // infection start time double recT; // scheduled recovery time }; These structs are kept in a special structure, InfectionMap: typedef boost::unordered_multimap< int, Infection > InfectionMap; Every member of class Host has an InfectionMap carriage. Recovery times and associated host identifiers are kept in a priority queue. When a scheduled recovery event arises in the simulation for a particular strain s in a particular host, the program searches through carriage of that host to find the Infection whose recT matches the recovery time (double recoverTime). (For reasons that aren't worth going into, it's not as expedient for me to use recT as the key to InfectionMap; the strain s is more useful, and coinfections with the same strain are possible.) assert( carriage.size() > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; for ( it = ret.first; it != ret.second; it++ ) { if ( ((*it).second).recT == recoverTime ) { // produces seg fault carriage.erase( it ); } } I get a "Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address..." on the line specified above. The recoverTime is fine, and the assert(...) in the code is not tripped. As I said, this seg fault appears 'randomly' after thousands of successful recovery events. How would you go about figuring out what's going on? I'd love ideas about what could be wrong and how I can further investigate the problem. Update I added a new assert and a check just inside the for loop: assert( carriage.size() > 0 ); assert( carriage.count( s ) > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; cout << "carriage.count(" << s << ")=" << carriage.count(s) << endl; for ( it = ret.first; it != ret.second; it++ ) { cout << "(*it).first=" << (*it).first << endl; // error here if ( ((*it).second).recT == recoverTime ) { carriage.erase( it ); } } The EXC_BAD_ACCESS error now appears at the (*it).first call, again after many thousands of successful recoveries. Can anyone give me tips on how to figure out how this problem arises? I'm trying to use gdb. Frame 0 from the backtrace reads "#0 0x0000000100001d50 in Host::recover (this=0x100530d80, s=0, recoverTime=635.91148029170529) at Host.cpp:317" I'm not sure what useful information I can extract here. Update 2 I added a break; after the carriage.erase(it). This works, but I have no idea why (e.g., why it would remove the seg fault at (*it).first.

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• Core Plot causing crash on device but not simulator.

  - by Eric

  I'm using core plot to create a small plot in one of my view controllers. I have been pulling my hair out trying to track down this error. I install on the simulator and it works fine but as soon as I put it on my device I get the following error: 2010-02-04 22:15:37.394 Achieve[127:207] *** -[NSCFString drawAtPoint:withTextStyle:inContext:]: unrecognized selector sent to instance 0x108530 2010-02-04 22:15:37.411 Achieve[127:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSCFString drawAtPoint:withTextStyle:inContext:]: unrecognized selector sent to instance 0x108530' 2010-02-04 22:15:37.427 Achieve[127:207] Stack: ( 843263261, 825818644, 843267069, 842763033, 842725440, 253481, 208187, 823956912, 823956516, 823956336, 823953488, 823952500, 823985628, 842717233, 843010887, 843009055, 860901832, 843738160, 843731504, 8797, 8692 ) terminate called after throwing an instance of 'NSException' Program received signal: “SIGABRT”. Debugger Output (as requested): #0 0x33b3db2c in __kill #1 0x33b3db20 in kill #2 0x33b3db14 in raise #3 0x33b54e3a in abort #4 0x33c5c398 in __gnu_cxx::__verbose_terminate_handler #5 0x313918a0 in _objc_terminate #6 0x33c59a8c in __cxxabiv1::__terminate #7 0x33c59b04 in std::terminate #8 0x33c59c2c in __cxa_throw #9 0x3138fe5c in objc_exception_throw #10 0x32433bfc in -[NSObject doesNotRecognizeSelector:] #11 0x323b8b18 in ___forwarding___ #12 0x323af840 in __forwarding_prep_0___ #13 0x0003de28 in -[CPTextLayer renderAsVectorInContext:] at CPTextLayer.m:117 #14 0x00032d3a in -[CPLayer drawInContext:] at CPLayer.m:146 #15 0x311c95b0 in -[CALayer _display] #16 0x311c9424 in -[CALayer display] #17 0x311c9370 in CALayerDisplayIfNeeded #18 0x311c8850 in CA::Context::commit_transaction #19 0x311c8474 in CA::Transaction::commit #20 0x311d05dc in CA::Transaction::observer_callback #21 0x323ad830 in __CFRunLoopDoObservers #22 0x323f5346 in CFRunLoopRunSpecific #23 0x323f4c1e in CFRunLoopRunInMode #24 0x335051c8 in GSEventRunModal #25 0x324a6c30 in -[UIApplication _run] #26 0x324a5230 in UIApplicationMain #27 0x0000225c in main at main.m:14 Here is my viewDidLoad method: - (void)viewDidLoad { [super viewDidLoad]; self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"bg.png"]]; [self loadData]; self.graph = [[CPXYGraph alloc] initWithFrame: self.plotView.frame]; CPLayerHostingView *hostingView = self.plotView; hostingView.hostedLayer = graph; graph.paddingLeft = 50; graph.paddingTop = 10; graph.paddingRight = 10; graph.paddingBottom = 10; percentFormatter = [[NSNumberFormatter alloc] init]; [percentFormatter setPercentSymbol:@"%"]; [percentFormatter setNumberStyle:NSNumberFormatterPercentStyle]; [percentFormatter setLocale: [NSLocale currentLocale]]; [percentFormatter setMultiplier:[NSNumber numberWithInt:1]]; [percentFormatter setMaximumFractionDigits:0]; CPXYPlotSpace *plotSpace = (CPXYPlotSpace *)graph.defaultPlotSpace; plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0) length:CPDecimalFromFloat(maxX)]; plotSpace.yRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(minY) length:CPDecimalFromFloat(maxY-minY)]; CPLineStyle *lineStyle = [[CPLineStyle lineStyle]retain]; lineStyle.lineColor = [CPColor grayColor]; lineStyle.lineWidth = 1.0f; CPTextStyle *whiteText = [CPTextStyle textStyle]; whiteText.color = [CPColor whiteColor]; CPXYAxisSet *axisSet = (CPXYAxisSet *)graph.axisSet; // axisSet.xAxis.majorIntervalLength = [[NSDecimalNumber decimalNumberWithString:@"0"]decimalValue]; axisSet.xAxis.minorTicksPerInterval = 0; axisSet.xAxis.majorTickLineStyle = nil; axisSet.xAxis.minorTickLineStyle = nil; axisSet.xAxis.axisLineStyle = lineStyle; axisSet.xAxis.minorTickLength = 0; axisSet.xAxis.majorTickLength = 0; axisSet.xAxis.labelFormatter = nil; axisSet.xAxis.labelTextStyle = nil; axisSet.yAxis.majorIntervalLength = [[NSDecimalNumber decimalNumberWithString:intY]decimalValue]; axisSet.yAxis.minorTicksPerInterval = 5; axisSet.yAxis.majorTickLineStyle = lineStyle; axisSet.yAxis.minorTickLineStyle = lineStyle; axisSet.yAxis.axisLineStyle = lineStyle; axisSet.yAxis.minorTickLength = 2.0f; axisSet.yAxis.majorTickLength = 4.0f; axisSet.yAxis.labelFormatter = percentFormatter; axisSet.yAxis.labelTextStyle = whiteText; CPScatterPlot *xSquaredPlot = [[[CPScatterPlot alloc]initWithFrame:graph.defaultPlotSpace.graph.bounds] autorelease]; xSquaredPlot.identifier = @"Plot"; xSquaredPlot.dataLineStyle.lineWidth = 4.0f; xSquaredPlot.dataLineStyle.lineColor = [CPColor yellowColor]; xSquaredPlot.dataSource = self; [graph addPlot:xSquaredPlot]; } Any help would be appreciated!

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• Objective-C: Scope problems cellForRowAtIndexPath

  - by Mr. McPepperNuts

  How would I set each individual row in cellForRowAtIndexPath to the results of an array populated by a Fetch Request? (Fetch Request made when button is pressed.) - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { // ... set up cell code here ... cell.textLabel.text = [results objectAtIndex:indexPath valueForKey:@"name"]; } warning: 'NSArray' may not respond to '-objectAtIndexPath:' Edit: - (NSArray *)SearchDatabaseForText:(NSString *)passdTextToSearchFor{ NSManagedObject *searchObj; XYZAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; NSManagedObjectContext *managedObjectContext = appDelegate.managedObjectContext; NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name contains [cd] %@", passdTextToSearchFor]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Entry" inManagedObjectContext:managedObjectContext]; NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [request setEntity: entity]; [request setPredicate: predicate]; NSError *error; results = [managedObjectContext executeFetchRequest:request error:&error]; // NSLog(@"results %@", results); if([results count] == 0){ NSLog(@"No results found"); searchObj = nil; self.tempString = @"No results found."; }else{ if ([[[results objectAtIndex:0] name] caseInsensitiveCompare:passdTextToSearchFor] == 0) { NSLog(@"results %@", [[results objectAtIndex:0] name]); searchObj = [results objectAtIndex:0]; }else{ NSLog(@"No results found"); self.tempString = @"No results found."; searchObj = nil; } } [tableView reloadData]; [request release]; [sortDescriptors release]; return results; } - (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar{ textToSearchFor = mySearchBar.text; results = [self SearchDatabaseForText:textToSearchFor]; self.tempString = [myGlobalSearchObject valueForKey:@"name"]; NSLog(@"results count: %d", [results count]); NSLog(@"results 0: %@", [[results objectAtIndex:0] name]); NSLog(@"results 1: %@", [[results objectAtIndex:1] name]); } @end Console prints: 2010-06-10 16:11:18.581 XYZApp[10140:207] results count: 2 2010-06-10 16:11:18.581 XYZApp[10140:207] results 0: BB Bugs 2010-06-10 16:11:18.582 XYZApp[10140:207] results 1: BB Annie Program received signal: “EXC_BAD_ACCESS”. (gdb) Edit 2: BT: #0 0x95a91edb in objc_msgSend () #1 0x03b1fe20 in ?? () #2 0x0043cd2a in -[UITableViewRowData(UITableViewRowDataPrivate) _updateNumSections] () #3 0x0043ca9e in -[UITableViewRowData invalidateAllSections] () #4 0x002fc82f in -[UITableView(_UITableViewPrivate) _updateRowData] () #5 0x002f7313 in -[UITableView noteNumberOfRowsChanged] () #6 0x00301500 in -[UITableView reloadData] () #7 0x00008623 in -[SearchViewController SearchDatabaseForText:] (self=0x3d16190, _cmd=0xf02b, passdTextToSearchFor=0x3b29630) #8 0x000086ad in -[SearchViewController searchBarSearchButtonClicked:] (self=0x3d16190, _cmd=0x16492cc, searchBar=0x3d2dc50) #9 0x0047ac13 in -[UISearchBar(UISearchBarStatic) _searchFieldReturnPressed] () #10 0x0031094e in -[UIControl(Deprecated) sendAction:toTarget:forEvent:] () #11 0x00312f76 in -[UIControl(Internal) _sendActionsForEventMask:withEvent:] () #12 0x0032613b in -[UIFieldEditor webView:shouldInsertText:replacingDOMRange:givenAction:] () #13 0x01d5a72d in __invoking___ () #14 0x01d5a618 in -[NSInvocation invoke] () #15 0x0273fc0a in SendDelegateMessage () #16 0x033168bf in -[_WebSafeForwarder forwardInvocation:] () #17 0x01d7e6f4 in ___forwarding___ () #18 0x01d5a6c2 in __forwarding_prep_0___ () #19 0x03320fd4 in WebEditorClient::shouldInsertText () #20 0x0279dfed in WebCore::Editor::shouldInsertText () #21 0x027b67a5 in WebCore::Editor::insertParagraphSeparator () #22 0x0279d662 in WebCore::EventHandler::defaultTextInputEventHandler () #23 0x0276cee6 in WebCore::EventTargetNode::defaultEventHandler () #24 0x0276cb70 in WebCore::EventTargetNode::dispatchGenericEvent () #25 0x0276c611 in WebCore::EventTargetNode::dispatchEvent () #26 0x0279d327 in WebCore::EventHandler::handleTextInputEvent () #27 0x0279d229 in WebCore::Editor::insertText () #28 0x03320f4d in -[WebHTMLView(WebNSTextInputSupport) insertText:] () #29 0x0279d0b4 in -[WAKResponder tryToPerform:with:] () #30 0x03320a33 in -[WebView(WebViewEditingActions) _performResponderOperation:with:] () #31 0x03320990 in -[WebView(WebViewEditingActions) insertText:] () #32 0x00408231 in -[UIWebDocumentView insertText:] () #33 0x003ccd31 in -[UIKeyboardImpl acceptWord:firstDelete:addString:] () #34 0x003d2c8c in -[UIKeyboardImpl addInputString:fromVariantKey:] () #35 0x004d1a00 in -[UIKeyboardLayoutStar sendStringAction:forKey:] () #36 0x004d0285 in -[UIKeyboardLayoutStar handleHardwareKeyDownFromSimulator:] () #37 0x002b5bcb in -[UIApplication handleEvent:withNewEvent:] () #38 0x002b067f in -[UIApplication sendEvent:] () #39 0x002b7061 in _UIApplicationHandleEvent () #40 0x02542d59 in PurpleEventCallback () #41 0x01d55b80 in CFRunLoopRunSpecific () #42 0x01d54c48 in CFRunLoopRunInMode () #43 0x02541615 in GSEventRunModal () #44 0x025416da in GSEventRun () #45 0x002b7faf in UIApplicationMain () #46 0x00002578 in main (argc=1, argv=0xbfffef5c) at /Users/default/Documents/iPhone Projects/XYZApp/main.m:14

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• C - circular character buffer w/ pthreads

  - by Matt

  I have a homework assignment where I have to implement a circular buffer and add and remove chars with separate threads: #include <pthread.h> #include <stdio.h> #define QSIZE 10 pthread_cond_t full,/* count == QSIZE */ empty,/* count == 0 */ ready; pthread_mutex_t m, n; /* implements critical section */ unsigned int iBuf, /* tail of circular queue */ oBuf; /* head of circular queue */ int count; /* count characters */ char buf [QSIZE]; /* the circular queue */ void Put(char s[]) {/* add "ch"; wait if full */ pthread_mutex_lock(&m); int size = sizeof(s)/sizeof(char); printf("size: %d", size); int i; for(i = 0; i < size; i++) { while (count >= QSIZE) pthread_cond_wait(&full, &m);/* is there empty slot? */ buf[iBuf] = s[i]; /* store the character */ iBuf = (iBuf+1) % QSIZE; /* increment mod QSIZE */ count++; if (count == 1) pthread_cond_signal(&empty);/* new character available */ } pthread_mutex_unlock(&m); } char Get() {/* remove "ch" from queue; wait if empty */ char ch; pthread_mutex_lock(&m); while (count <= 0) pthread_cond_wait(&empty, &m);/* is a character present? */ ch = buf[oBuf]; /* retrieve from the head of the queue */ oBuf = (oBuf+1) % QSIZE; count--; if (count == QSIZE-1) pthread_cond_signal(&full);/* signal existence of a slot */ pthread_mutex_unlock(&m); return ch; } void * p1(void *arg) { int i; for (i = 0; i < 5; i++) { Put("hella"); } } void * p2(void *arg) { int i; for (i = 0; i < 5; i++) { Put("goodby"); } } int main() { pthread_t t1, t2; void *r1, *r2; oBuf = 0; iBuf = 0; count=0; /* all slots are empty */ pthread_cond_init(&full, NULL); pthread_cond_init(&empty, NULL); pthread_mutex_init(&m, NULL); pthread_create(&t1, NULL, p1, &r1); pthread_create(&t2, NULL, p2, &r2); printf("Main"); char c; int i = 0; while (i < 55) { c = Get(); printf("%c",c); i++; } pthread_join(t1, &r1); pthread_join(t2, &r2); return 0; } I shouldn't have to change the logic much at all, the requirements are pretty specific. I think my problem lies in the Put() method. I think the first thread is going in and blocking the critical section and causing a deadlock. I was thinking I should make a scheduling attribute? Of course I could be wrong. I am pretty new to pthreads and concurrent programming, so I could really use some help spotting my error.

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• Simple Detached pThread does not cancel! (cout blocks and interleaves even if mutexed)

  - by Gabriel

  I have a hard problem here, which I can not solve and do not find the right answer on the net: I have created a detached thread with a clean up routing, the problem is that on my Imac and Ubuntu 9.1 (Dual Core). I am not able to correctly cancel the detached thread in the fallowing code: #include <iostream> #include <pthread.h> #include <sched.h> #include <signal.h> #include <time.h> pthread_mutex_t mutex_t; using namespace std; static void cleanup(void *arg){ pthread_mutex_lock(&mutex_t); cout << " doing clean up"<<endl; pthread_mutex_unlock(&mutex_t); } static void *thread(void *aArgument) { pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,NULL); pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED,NULL); pthread_cleanup_push(&cleanup,NULL); int n=0; while(1){ pthread_testcancel(); sched_yield(); n++; pthread_mutex_lock(&mutex_t); cout << " Thread 2: "<< n<<endl; pthread_mutex_unlock(&mutex_t); } pthread_cleanup_pop(0); return NULL; } int main() { pthread_t thread_id; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED); int error; if (pthread_mutex_init(&mutex_t,NULL) != 0) return 1; if (pthread_create(&thread_id, &attr, &(thread) , NULL) != 0) return 1; pthread_mutex_lock(&mutex_t); cout << "waiting 1s for thread...\n" <<endl; pthread_mutex_unlock(&mutex_t); int n =0; while(n<1E3){ pthread_testcancel(); sched_yield(); n++; pthread_mutex_lock(&mutex_t); cout << " Thread 1: "<< n<<endl; pthread_mutex_unlock(&mutex_t); } pthread_mutex_lock(&mutex_t); cout << "canceling thread...\n" <<endl; pthread_mutex_unlock(&mutex_t); if (pthread_cancel(thread_id) == 0) { //This doesn't wait for the thread to exit pthread_mutex_lock(&mutex_t); cout << "detaching thread...\n"<<endl; pthread_mutex_unlock(&mutex_t); pthread_detach(thread_id); while (pthread_kill(thread_id,0)==0) { sched_yield(); } pthread_mutex_lock(&mutex_t); cout << "thread is canceled"; pthread_mutex_unlock(&mutex_t); } pthread_mutex_lock(&mutex_t); cout << "exit"<<endl; pthread_mutex_unlock(&mutex_t); return 0; } When I replace the Cout with printf() i workes to the end "exit" , but with the cout (even locked) the executable hangs after outputting "detaching thread... It would be very cool to know from a Pro, what the problem here is?. Why does this not work even when cout is locked by a mutex!? Thanks a lot for your support!!

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• multple inner joins 3 or more crashes mysql server 5.1.30 opensolaris

  - by user331849

  when doing simple query on 4 inner joined tables, the server crashes with the output below appearing in the the mysql .err file. eg. select * from table1 inner join table2 on table1.a = table2.a and table1.b = table2.b inner join table3 on table2.a = table3.a and table2.c = table3.c inner join table4 on table3.a = table4.a and table3.d = table4.d If i remove one of the tables it executes fine. Likewise if I remove a different table, it executes fine. Though all tables have been checked anyway, this would suggest that it is not a problem specifically with one of the tables. mysql.err trace: 100503 18:13:19 - mysqld got signal 11 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail. key_buffer_size=1572864000 read_buffer_size=2097152 max_used_connections=11 max_threads=151 threads_connected=10 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 2155437 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. thd: 0x72febda8 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... stack_bottom = fe07efb0 thread_stack 0x40000 Trying to get some variables. Some pointers may be invalid and cause the dump to abort... thd-query at be1021f0 = explain select * from business inner join timetable on business.id = timetable.business_id inner join timetableentry on timetable.business_id = timetableentry.business_id and timetable.kid = timetableentry.parent inner join staff on timetable.business_id = staff.business_id and timetable.staf f_person = staff.kid where business.id = '3050bb04fda41df64a9c1c149150026c' thd-thread_id=9 thd-killed=NOT_KILLED The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains information that should help you find out what is causing the crash. 100503 18:13:19 mysqld_safe mysqld restarted 100503 18:13:20 InnoDB: Failed to set DIRECTIO_ON on file ./ibdata1: OPEN: Inap propriate ioctl for device, continuing anyway 100503 18:13:20 InnoDB: Failed to set DIRECTIO_ON on file ./ibdata1: OPEN: Inap propriate ioctl for device, continuing anyway InnoDB: The log sequence number in ibdata files does not match InnoDB: the log sequence number in the ib_logfiles! 100503 18:13:20 InnoDB: Database was not shut down normally! InnoDB: Starting crash recovery. InnoDB: Reading tablespace information from the .ibd files... InnoDB: Restoring possible half-written data pages from the doublewrite InnoDB: buffer... InnoDB: Last MySQL binlog file position 0 2731, file name ./mysql-bin.000093 100503 18:13:20 InnoDB: Started; log sequence number 0 2650338426 100503 18:13:20 [Note] Recovering after a crash using mysql-bin 100503 18:13:20 [Note] Starting crash recovery... 100503 18:13:20 [Note] Crash recovery finished. This on opensolaris SunOS 5.11 snv_111b i86pc i386 i86pc Mysql 5.1.30 Here is a snippet from the my.cnf file: key_buffer = 1500M max_allowed_packet = 1M thread_stack = 256K thread_cache_size = 8 sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 8M table_cache = 512 tmp_table_size = 400M max_heap_table_size = 64M query_cache_limit = 20M query_cache_size = 200M Is this a bug or a configuration issue?

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• Survey Data Model - How to avoid EAV and excessive denormalization?

  - by AlexDPC

  Hi everyone, My database skills are mediocre at best and I have to design a data model for survey data. I have spent some thoughts on this and right now I feel that I am stuck between some kind of EAV model and a design involving hundreds of tables, each with hundreds of columns (and thousands of records). There must be a better way to do this and I hope that the wise folks on this forum can help me. I have already searched various forums, but I couldn't really find a solution. If it has already been given elsewhere, please excuse me and provide me with a link so I can read it up. Some assumptions about the data I have to deal with: Each survey consists of 1 to n questionnaires Each questionnaire consists of 100-2,000 questions (please ignore that 2,000 questions really sound like a lot to answer...) Questions can be of various types: multiple-choice, free text, a number (like age, income, percentages, ...) Each survey involves 10-200 countries (These are not the respondents. The respondents are actually people in the countries.) Depending on the type of questionnaire, each questionnaire is answered by 100-20,000 respondents per country. A country can adapt the questionnaires for a survey, i.e. add, remove or edit questions The data for one country is gathered in a separate database in that country. There is no possibility for online integration from the start. The data for all countries has to be integrated later. This means for example, if a country has deleted a question, that data must somehow be derived from what they sent in order to achieve a uniform design across all countries I will have to write the integration and cleaning software, which will need to work with every country's data In the end the data needs to be exported to flat files, one rectangular grid per country and questionnaire. I have already discussed this topic with people from various backgrounds and have not come to a good solution yet. I mainly got two kinds of opinions. The domain experts, who are used to working with flat files (spreadsheet-style) for data processing and analysis vote for a denormalized structure with loads of tables and columns as I described above (1 table per country and questionnaire). This sounds terrible to me, because I learned that wide tables are to be avoided, it will be annoying to determine which columns are actually in a table when working with it, the database will become cluttered with hundreds of tables (or I even need to set up multiple databases, each with a similar yet a bit differetn design), etc. O-O-programmers vote for a strongly "normalized" design, which would effectively lead to a central table containing all the answers from all respondents to all questions. This table would either need to contain a column of type sql_variant type or multiple answer columns with different types to store answers of different types (multiple choice, free text, ..). The former would essentially be a EAV model. I tend to follow Joe Celko here, who strongly discourages its use (he calls it OTLT or "One True Lookup Table"). The latter would imply that each row would contain null cells for the not applicable types by design. Another alternative I could think of would be to create one table per answer type, i.e., one for multiple-choice questions, one for free text questions, etc.. That's not so generic, it would lead to a lot of union joins, I think and I would have to add a table if a new answer type is invented. Sorry for boring you with all this text and thank you for your input! Cheers, Alex PS: I asked the same question here: http://www.eggheadcafe.com/community/aspnet/13/10242616/survey-data-model--how-to-avoid-eav-and-excessive-denormalization.aspx

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• Node.js, Cygwin and Socket.io walk into a bar... Node.js throws ENOBUFS and everyone dies...

  - by A Wizard Did It

  I'm hoping someone here can help me out, I'm not having much luck figuring this out myself. I'm running node.js version 0.3.1 on Cygwin. I'm using Connect and Socket.io. I seem to be having some random problems with DNS or something, I haven't quite figured it out. The end result is that I the server is running fine, but when a browser attempts to connect to it the initial HTTP Request works, Socket.io connects, and then the server dies (output below). I don't think it has anything to do with the HTTP request because the server gets a lot data posted to it, and it was receiving requests and responding up until my connection that killed it. I've googled around and the closest thing I've found is DNS being set improperly. It's a network program meant to run only on an internal network, so I've set the nameserver x.x.x.x in my /etc/resolv.conf to the internal DNS. I've also added nameserver 8.8.8.8 in addition. I'm not sure what else to check, but would be grateful of any help. In node.exe.stackdump Exception: STATUS_ACCESS_VIOLATION at eip=610C51B9 eax=00000000 ebx=00000001 ecx=00000000 edx=00000308 esi=00000000 edi=010FCCB0 ebp=010FCAEC esp=010FCAC4 program=\\?\E:\cygwin\usr\local\bin\node.exe, pid 3296, thread unknown (0xBEC) cs=0023 ds=002B es=002B fs=0053 gs=002B ss=002B Stack trace: Frame Function Args 010FCAEC 610C51B9 (00000000, 00000000, 00000000, 00000000) 010FCBFC 610C5B55 (00000000, 00000000, 00000000, 00000000) 010FCCBC 610C693A (FFFFFFFF, FFFFFFFF, 750334F3, FFFFFFFE) 010FCD0C 61027CB2 (00000002, F4B994D5, 010FCE64, 00000002) 010FCD98 76306B59 (00000002, 010FCDD4, 763069A4, 00000002) End of stack trace Node Output: node.js:50 throw e; // process.nextTick error, or 'error' event on first tick ^ Error: ENOBUFS, No buffer space available at doConnect (net.js:642:19) at net.js:803:9 at dns.js:166:30 at IOWatcher.callback (dns.js:48:15) EDIT I'm hitting an LDAP server using http.createClient immediately after a client connects to get information, and that seems to be where the problem is that is causing ENOBUFS. I've edited the source to include && errno != ENOBUFS which now prevents the server from dying, however now the LDAP request isn't working. I'm not sure what the problem is that would cause that though. As I mentioned this is an internal only application, so I set the DNS servers in /etc/resolv.conf to the DNS servers that are being applied to the host machine. Not sure if this is part of the issue? EDIT 2 Here's some output from gdb --args ./node_g --debug ../myscript.js. I'm not sure if this is related to ENOBUFS, however, as it seems to be disconnecting immediately after connection with Socket.io [New thread 672.0x100] Error: dll starting at 0x76e30000 not found. Error: dll starting at 0x76250000 not found. Error: dll starting at 0x76e30000 not found. Error: dll starting at 0x76f50000 not found. [New thread 672.0xc90] [New thread 672.0x448] debugger listening on port 5858 [New thread 672.0xbf4] 14 Jan 18:48:57 - socket.io ready - accepting connections [New thread 672.0xed4] [New thread 672.0xd68] [New thread 672.0x1244] [New thread 672.0xf14] 14 Jan 18:49:02 - Initializing client with transport "websocket" assertion "b[1] == 0" failed: file "../src/node.cc", line 933, function: ssize_t node::DecodeWrite(char*, size_t, v8::Handle<v8::Value>, node::encoding) Program received signal SIGABRT, Aborted. 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll (gdb) backtrace #0 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll #1 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll #2 0x75030816 in WaitForSingleObjectEx () from /cygdrive/c/Windows/syswow64/KernelBase.dll #3 0x0000035c in ?? () #4 0x00000000 in ?? () (gdb)

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• PHP script causes segmentation fault then the browser asks me to download the .php file with nothing in it?

  - by John

  I've noticed an unusual problem with some of my php programs. Sometimes when visiting a page like profile.edit.php, the browser throws a dialogue box asking to download profile.edit.php page. When I download it, there's nothing in the file. profile.edit.php is supposed to be a web form that edits user information. I've noticed this on some of my other php pages as well. I look in my apache error logs, and I see a segmentation fault message: [Mon Mar 08 15:40:10 2010] [notice] child pid 480 exit signal Segmentation fault (11) And also, the issue may or may not appear depending on which server I deploy my application too. Additonal Details This doesn't happen all the time though. It only happens sometimes. For example, profile.edit.php will load properly. But as soon as I hit the save button (form action="profile.edit.php?save=true"), then the page asks me to download profile.edit.php. Could it be that sometimes my php scripts consume too much resources? Sample code Upon save action, my profile.edit.php includes a data_access_object.php file. I traced the code in data_access_object.php to this line here if($params[$this->primaryKey]) { $q = "UPDATE $this->tableName SET ".implode(', ', $fields)." WHERE ".$this->primaryKey." = ?$this->primaryKey"; $this->bind($this->primaryKey, $params[$this->primaryKey], $this->tblFields[$this->primaryKey]['mysqlitype']); } else { $q = "INSERT $this->tableName SET ".implode(', ', $fields); } // Code executes perfectly up to this point // echo 'print this'; exit; // if i uncomment this line, profile.edit.php will actually show 'print this'. If I leave it commented, the browser will ask me to download profile.edit.php if(!$this->execute($q)){ $this->errorSave = -3; return false;} // When I jumped into the function execute(), every line executed as expected, right up to the return statement. And if it helps, here's the function execute($sql) in data_access_object.php function execute($sql) { // find all list types and explode them // eg. turn ?listId into ?listId0,?listId1,?listId2 $arrListParam = array_bubble_up('arrayName', $this->arrBind); foreach($arrListParam as $listName) if($listName) { $explodeParam = array(); $arrList = $this->arrBind[$listName]['value']; foreach($arrList as $key=>$val) { $newParamName = $listName.$key; $this->bind($newParamName,$val,$this->arrBind[$listName]['type']); $explodeParam[] = '?'.$newParamName; } $sql = str_replace("?$listName", implode(',',$explodeParam), $sql); } // replace all ?varName with ? for syntax compliance $sqlParsed = preg_replace('/\?[\w\d_\.]+/', '?', $sql); $this->stmt->prepare($sqlParsed); // grab all the parameters from the sql to create bind conditions preg_match_all('/\?[\w\d_\.]+/', $sql, $matches); $matches = $matches[0]; // store bind conditions $types = ''; $params = array(); foreach($matches as $paramName) { $types .= $this->arrBind[str_replace('?', '', $paramName)]['type']; $params[] = $this->arrBind[str_replace('?', '', $paramName)]['value']; } $input = array('types'=>$types) + $params; // bind it if(!empty($types)) call_user_func_array(array($this->stmt, 'bind_param'), $input); $stat = $this->stmt->execute(); if($GLOBALS['DEBUG_SQL']) echo '<p style="font-weight:bold;">SQL error after execution:</p> ' . $this->stmt->error.'<p>&nbsp;</p>'; $this->arrBind = array(); return $stat; }

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• Application shows low memory warning and crashes while loading images?

  - by Bhoomi

  I am using following code for loading images from server using following code.When i scroll UITableView application crashes. AsynchrohousImageView class .m file - (void)dealloc { [connection cancel]; //in case the URL is still downloading [connection release]; [data release]; [_imageView release]; [_activityIndicator release]; [super dealloc]; } - (void)loadImageFromURL:(NSURL*)url defaultImageName:(NSString *)defaultImageName showDefaultImage:(BOOL)defaultImageIsShown showActivityIndicator:(BOOL)activityIndicatorIsShown activityIndicatorRect:(CGRect)activityIndicatorRect activityIndicatorStyle:(UIActivityIndicatorViewStyle)activityIndicatorStyle { if (connection!=nil) { [connection release]; } if (data!=nil) { [data release]; } if ([[self subviews] count]>0) { [[[self subviews] objectAtIndex:0] removeFromSuperview]; // } if (defaultImageIsShown) { self.imageView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:defaultImageName]] autorelease]; } else { self.imageView = [[[UIImageView alloc] init] autorelease]; } [self addSubview:_imageView]; _imageView.frame = self.bounds; [_imageView setNeedsLayout]; [self setNeedsLayout]; if (activityIndicatorIsShown) { self.activityIndicator = [[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:activityIndicatorStyle] autorelease]; [self addSubview:_activityIndicator]; _activityIndicator.frame = activityIndicatorRect; _activityIndicator.center = CGPointMake(_imageView.frame.size.width/2, _imageView.frame.size.height/2); [_activityIndicator setHidesWhenStopped:YES]; [_activityIndicator startAnimating]; } NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0]; connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; } - (void)connection:(NSURLConnection *)theConnection didReceiveData:(NSData *)incrementalData { if (data==nil) { data = [[NSMutableData alloc] initWithCapacity:2048]; } [data appendData:incrementalData]; } - (void)connectionDidFinishLoading:(NSURLConnection*)theConnection { [connection release]; connection=nil; _imageView.image = [UIImage imageWithData:data]; if (_activityIndicator) { [_activityIndicator stopAnimating]; } [data release]; data=nil; } - (UIImage*) image { UIImageView* iv = [[self subviews] objectAtIndex:0]; return [iv image]; } In ViewController Class Which loads image - (UITableViewCell *)tableView:(UITableView *)tV cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *reuseIdentifier =@"CellIdentifier"; ListCell *cell = (ListCell *)[tableView dequeueReusableCellWithIdentifier:reuseIdentifier]; if (cell==nil) { cell = [[ListCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier]; NSMutableDictionary *dicResult = [arrResults objectAtIndex:indexPath.row]; NSURL *url=[NSURL URLWithString:[dicResult objectForKey:@"Image"]]; AsynchronousImageView *asyncImageView = [[AsynchronousImageView alloc] initWithFrame:CGRectMake(5, 10,80,80)]; [asyncImageView loadImageFromURL:url defaultImageName:@"DefaultImage.png" showDefaultImage:NO showActivityIndicator:YES activityIndicatorRect:CGRectMake(5, 10,30,30) activityIndicatorStyle:UIActivityIndicatorViewStyleGray]; // load our image with URL asynchronously [cell.contentView addSubview:asyncImageView]; // cell.imgLocationView.image = [UIImage imageNamed:[dicResult valueForKey:@"Image"]]; [asyncImageView release]; } if([arrResults count]==1) { UITableViewCell *cell1=[tableView dequeueReusableCellWithIdentifier:reuseIdentifier]; if(cell1==nil) cell1=[[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier] autorelease]; NSMutableDictionary *dicResult = [arrResults objectAtIndex:0]; cell1.textLabel.text=[dicResult valueForKey:@"NoResults"]; return cell1; } else { NSMutableDictionary *dicResult = [arrResults objectAtIndex:indexPath.row]; NSString *title = [NSString stringWithFormat:@"%@ Bedrooms-%@", [dicResult valueForKey:KEY_NUMBER_OF_BEDROOMS],[dicResult valueForKey:KEY_PROPERTY_TYPE]]; NSString *strAddress = [dicResult valueForKey:KEY_DISPLAY_NAME]; NSString *address = [strAddress stringByReplacingOccurrencesOfString:@", " withString:@"\n"]; NSString *price = [dicResult valueForKey:KEY_PRICE]; NSString *distance = [dicResult valueForKey:KEY_DISTANCE]; cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; cell.lblTitle.text = title; cell.lblAddress.text = address; if ([price length]>0) { cell.lblPrice.text = [NSString stringWithFormat:@"£%@",price]; }else{ cell.lblPrice.text = @""; } if ([distance length]>0) { cell.lblmiles.text = [NSString stringWithFormat:@"%.2f miles",[distance floatValue]]; }else{ cell.lblmiles.text = @""; } } return cell; } How can i resolve this? I have attached heapshot analysis screen shot of it.Here non Object consumes so much of memory what is that?

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• Do you know of a C macro to compute Unix time and date?

  - by Alexis Wilke

  I'm wondering if someone knows/has a C macro to compute a static Unix time from a hard coded date and time as in: time_t t = UNIX_TIMESTAMP(2012, 5, 10, 9, 26, 13); I'm looking into that because I want to have a numeric static timestamp. This will be done hundred of times throughout the software, each time with a different date, and I want to make sure it is fast because it will run hundreds of times every second. Converting dates that many times would definitively slow down things (i.e. calling mktime() is slower than having a static number compiled in place, right?) [made an update to try to render this paragraph clearer, Nov 23, 2012] Update I want to clarify the question with more information about the process being used. As my server receives requests, for each request, it starts a new process. That process is constantly updated with new plugins and quite often such updates require a database update. Those must be run only once. To know whether an update is necessary, I want to use a Unix date (which is better than using a counter because a counter is much more likely to break once in a while.) The plugins will thus receive an update signal and have their on_update() function called. There I want to do something like this: void some_plugin::on_update(time_t last_update) { if(last_update < UNIX_TIMESTAMP(2010, 3, 22, 20, 9, 26)) { ...run update... } if(last_update < UNIX_TIMESTAMP(2012, 5, 10, 9, 26, 13)) { ...run update... } // as many test as required... } As you can see, if I have to compute the unix timestamp each time, this could represent thousands of calls per process and if you receive 100 hits a second x 1000 calls, you wasted 100,000 calls when you could have had the compiler compute those numbers once at compile time. Putting the value in a static variable is of no interest because this code will run once per process run. Note that the last_update variable changes depending on the website being hit (it comes from the database.) Code Okay, I got the code now: // helper (Days in February) #define _SNAP_UNIX_TIMESTAMP_FDAY(year) \ (((year) % 400) == 0 ? 29LL : \ (((year) % 100) == 0 ? 28LL : \ (((year) % 4) == 0 ? 29LL : \ 28LL))) // helper (Days in the year) #define _SNAP_UNIX_TIMESTAMP_YDAY(year, month, day) \ ( \ /* January */ static_cast<qint64>(day) \ /* February */ + ((month) >= 2 ? 31LL : 0LL) \ /* March */ + ((month) >= 3 ? _SNAP_UNIX_TIMESTAMP_FDAY(year) : 0LL) \ /* April */ + ((month) >= 4 ? 31LL : 0LL) \ /* May */ + ((month) >= 5 ? 30LL : 0LL) \ /* June */ + ((month) >= 6 ? 31LL : 0LL) \ /* July */ + ((month) >= 7 ? 30LL : 0LL) \ /* August */ + ((month) >= 8 ? 31LL : 0LL) \ /* September */+ ((month) >= 9 ? 31LL : 0LL) \ /* October */ + ((month) >= 10 ? 30LL : 0LL) \ /* November */ + ((month) >= 11 ? 31LL : 0LL) \ /* December */ + ((month) >= 12 ? 30LL : 0LL) \ ) #define SNAP_UNIX_TIMESTAMP(year, month, day, hour, minute, second) \ ( /* time */ static_cast<qint64>(second) \ + static_cast<qint64>(minute) * 60LL \ + static_cast<qint64>(hour) * 3600LL \ + /* year day (month + day) */ (_SNAP_UNIX_TIMESTAMP_YDAY(year, month, day) - 1) * 86400LL \ + /* year */ (static_cast<qint64>(year) - 1970LL) * 31536000LL \ + ((static_cast<qint64>(year) - 1969LL) / 4LL) * 86400LL \ - ((static_cast<qint64>(year) - 1901LL) / 100LL) * 86400LL \ + ((static_cast<qint64>(year) - 1601LL) / 400LL) * 86400LL ) WARNING: Do not use these macros to dynamically compute a date. It is SLOWER than mktime(). This being said, if you have a hard coded date, then the compiler will compute the time_t value at compile time. Slower to compile, but faster to execute over and over again.

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