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• java: how to compress data into a String and uncompress data from the String

  - by Guillaume

  I want to put some compressed data into a remote repository. To put data on this repository I can only use a method that take the name of the resource and its content as a String. (like data.txt + "hello world"). The repository is moking a filesystem but is not, so I can not use File directly. I want to be able to do the following: client send to server a file 'data.txt' server compress 'data.txt' into data.zip server send to repository content of data.zip repository store data.zip client download from repository data.zip and his able to open it with its favorite zip tool I have tried a lots of compressing example found on the web but each time a send the data to the repository, my resulting zip file is corrupted. Here is a sample class, using the zip*stream and that emulate the repository showcasing my problem. The created zip file is working, but after its 'serialization' it's get corrupted. (the sample class use jakarta commons.io ) Many thanks for your help. package zip; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.zip.ZipEntry; import java.util.zip.ZipInputStream; import java.util.zip.ZipOutputStream; import org.apache.commons.io.FileUtils; /** * Date: May 19, 2010 - 6:13:07 PM * * @author Guillaume AME. */ public class ZipMe { public static void addOrUpdate(File zipFile, File ... files) throws IOException { File tempFile = File.createTempFile(zipFile.getName(), null); // delete it, otherwise you cannot rename your existing zip to it. tempFile.delete(); boolean renameOk = zipFile.renameTo(tempFile); if (!renameOk) { throw new RuntimeException("could not rename the file " + zipFile.getAbsolutePath() + " to " + tempFile.getAbsolutePath()); } byte[] buf = new byte[1024]; ZipInputStream zin = new ZipInputStream(new FileInputStream(tempFile)); ZipOutputStream out = new ZipOutputStream(new FileOutputStream(zipFile)); ZipEntry entry = zin.getNextEntry(); while (entry != null) { String name = entry.getName(); boolean notInFiles = true; for (File f : files) { if (f.getName().equals(name)) { notInFiles = false; break; } } if (notInFiles) { // Add ZIP entry to output stream. out.putNextEntry(new ZipEntry(name)); // Transfer bytes from the ZIP file to the output file int len; while ((len = zin.read(buf)) > 0) { out.write(buf, 0, len); } } entry = zin.getNextEntry(); } // Close the streams zin.close(); // Compress the files if (files != null) { for (File file : files) { InputStream in = new FileInputStream(file); // Add ZIP entry to output stream. out.putNextEntry(new ZipEntry(file.getName())); // Transfer bytes from the file to the ZIP file int len; while ((len = in.read(buf)) > 0) { out.write(buf, 0, len); } // Complete the entry out.closeEntry(); in.close(); } // Complete the ZIP file } tempFile.delete(); out.close(); } public static void main(String[] args) throws IOException { final String zipArchivePath = "c:/temp/archive.zip"; final String tempFilePath = "c:/temp/data.txt"; final String resultZipFile = "c:/temp/resultingArchive.zip"; File zipArchive = new File(zipArchivePath); FileUtils.touch(zipArchive); File tempFile = new File(tempFilePath); FileUtils.writeStringToFile(tempFile, "hello world"); addOrUpdate(zipArchive, tempFile); //archive.zip exists and contains a compressed data.txt that can be read using winrar //now simulate writing of the zip into a in memory cache String archiveText = FileUtils.readFileToString(zipArchive); FileUtils.writeStringToFile(new File(resultZipFile), archiveText); //resultingArchive.zip exists, contains a compressed data.txt, but it can not //be read using winrar: CRC failed in data.txt. The file is corrupt } }

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• java: how to get a string representation of a compressed byte array ?

  - by Guillaume

  I want to put some compressed data into a remote repository. To put data on this repository I can only use a method that take the name of the resource and its content as a String. (like data.txt + "hello world"). The repository is moking a filesystem but is not, so I can not use File directly. I want to be able to do the following: client send to server a file 'data.txt' server compress 'data.txt' into a compressed file 'data.zip' server send a string representation of data.zip to the repository repository store data.zip client download from repository data.zip and his able to open it with its favorite zip tool The problem arise at step 3 when I try to get a string representation of my compressed file. Here is a sample class, using the zip*stream and that emulate the repository showcasing my problem. The created zip file is working, but after its 'serialization' it's get corrupted. (the sample class use jakarta commons.io ) Many thanks for your help. package zip; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.zip.ZipEntry; import java.util.zip.ZipInputStream; import java.util.zip.ZipOutputStream; import org.apache.commons.io.FileUtils; /** * Date: May 19, 2010 - 6:13:07 PM * * @author Guillaume AME. */ public class ZipMe { public static void addOrUpdate(File zipFile, File ... files) throws IOException { File tempFile = File.createTempFile(zipFile.getName(), null); // delete it, otherwise you cannot rename your existing zip to it. tempFile.delete(); boolean renameOk = zipFile.renameTo(tempFile); if (!renameOk) { throw new RuntimeException("could not rename the file " + zipFile.getAbsolutePath() + " to " + tempFile.getAbsolutePath()); } byte[] buf = new byte[1024]; ZipInputStream zin = new ZipInputStream(new FileInputStream(tempFile)); ZipOutputStream out = new ZipOutputStream(new FileOutputStream(zipFile)); ZipEntry entry = zin.getNextEntry(); while (entry != null) { String name = entry.getName(); boolean notInFiles = true; for (File f : files) { if (f.getName().equals(name)) { notInFiles = false; break; } } if (notInFiles) { // Add ZIP entry to output stream. out.putNextEntry(new ZipEntry(name)); // Transfer bytes from the ZIP file to the output file int len; while ((len = zin.read(buf)) > 0) { out.write(buf, 0, len); } } entry = zin.getNextEntry(); } // Close the streams zin.close(); // Compress the files if (files != null) { for (File file : files) { InputStream in = new FileInputStream(file); // Add ZIP entry to output stream. out.putNextEntry(new ZipEntry(file.getName())); // Transfer bytes from the file to the ZIP file int len; while ((len = in.read(buf)) > 0) { out.write(buf, 0, len); } // Complete the entry out.closeEntry(); in.close(); } // Complete the ZIP file } tempFile.delete(); out.close(); } public static void main(String[] args) throws IOException { final String zipArchivePath = "c:/temp/archive.zip"; final String tempFilePath = "c:/temp/data.txt"; final String resultZipFile = "c:/temp/resultingArchive.zip"; File zipArchive = new File(zipArchivePath); FileUtils.touch(zipArchive); File tempFile = new File(tempFilePath); FileUtils.writeStringToFile(tempFile, "hello world"); addOrUpdate(zipArchive, tempFile); //archive.zip exists and contains a compressed data.txt that can be read using winrar //now simulate writing of the zip into a in memory cache String archiveText = FileUtils.readFileToString(zipArchive); FileUtils.writeStringToFile(new File(resultZipFile), archiveText); //resultingArchive.zip exists, contains a compressed data.txt, but it can not //be read using winrar: CRC failed in data.txt. The file is corrupt } }

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• Couldn't match expected type - Haskell Code

  - by wvyar

  I'm trying to learn Haskell, but the small bit of sample code I tried to write is running into a fairly large amount of "Couldn't match expected type" errors. Can anyone give me some guidance as to what I'm doing wrong/how I should go about this? These are the errors, but I'm not really sure how I should be writing my code. toDoSchedulerSimple.hs:6:14: Couldn't match expected type `[t0]' with actual type `IO String' In the return type of a call of `readFile' In a stmt of a 'do' block: f <- readFile inFile In the expression: do { f <- readFile inFile; lines f } toDoSchedulerSimple.hs:27:9: Couldn't match expected type `[a0]' with actual type `IO ()' In the return type of a call of `putStr' In a stmt of a 'do' block: putStr "Enter task name: " In the expression: do { putStr "Enter task name: "; task <- getLine; return inFileArray : task } toDoSchedulerSimple.hs:34:9: Couldn't match expected type `IO ()' with actual type `[a0]' In a stmt of a 'do' block: putStrLn "Your task is: " ++ (inFileArray !! i) In the expression: do { i <- randomRIO (0, (length inFileArray - 1)); putStrLn "Your task is: " ++ (inFileArray !! i) } In an equation for `getTask': getTask inFileArray = do { i <- randomRIO (0, (length inFileArray - 1)); putStrLn "Your task is: " ++ (inFileArray !! i) } toDoSchedulerSimple.hs:41:9: Couldn't match expected type `[a0]' with actual type `IO ()' In the return type of a call of `putStr' In a stmt of a 'do' block: putStr "Enter the task you would like to end: " In the expression: do { putStr "Enter the task you would like to end: "; task <- getLine; filter (endTaskCheck task) inFileArray } toDoSchedulerSimple.hs:60:53: Couldn't match expected type `IO ()' with actual type `[String] -> IO ()' In a stmt of a 'do' block: schedulerSimpleMain In the expression: do { (getTask inFileArray); schedulerSimpleMain } In a case alternative: "get-task" -> do { (getTask inFileArray); schedulerSimpleMain } This is the code itself. I think it's fairly straightforward, but the idea is to run a loop, take input, and perform actions based off of it by calling other functions. import System.Random (randomRIO) import Data.List (lines) initializeFile :: [char] -> [String] initializeFile inFile = do f <- readFile inFile let parsedFile = lines f return parsedFile displayHelp :: IO() displayHelp = do putStrLn "Welcome to To Do Scheduler Simple, written in Haskell." putStrLn "Here are some commands you might find useful:" putStrLn " 'help' : Display this menu." putStrLn " 'quit' : Exit the program." putStrLn " 'new-task' : Create a new task." putStrLn " 'get-task' : Randomly select a task." putStrLn " 'end-task' : Mark a task as finished." putStrLn " 'view-tasks' : View all of your tasks." quit :: IO() quit = do putStrLn "We're very sad to see you go...:(" putStrLn "Come back soon!" createTask :: [String] -> [String] createTask inFileArray = do putStr "Enter task name: " task <- getLine return inFileArray:task getTask :: [String] -> IO() getTask inFileArray = do i <- randomRIO (0, (length inFileArray - 1)) putStrLn "Your task is: " ++ (inFileArray !! i) endTaskCheck :: String -> String -> Bool endTaskCheck str1 str2 = str1 /= str2 endTask :: [String] -> [String] endTask inFileArray = do putStr "Enter the task you would like to end: " task <- getLine return filter (endTaskCheck task) inFileArray viewTasks :: [String] -> IO() viewTasks inFileArray = case inFileArray of [] -> do putStrLn "\nEnd of tasks." _ -> do putStrLn (head inFileArray) viewTasks (tail inFileArray) schedulerSimpleMain :: [String] -> IO() schedulerSimpleMain inFileArray = do putStr "SchedulerSimple> " input <- getLine case input of "help" -> displayHelp "quit" -> quit "new-task" -> schedulerSimpleMain (createTask inFileArray) "get-task" -> do (getTask inFileArray); schedulerSimpleMain "end-task" -> schedulerSimpleMain (endTask inFileArray) "view-tasks" -> do (viewTasks inFileArray); schedulerSimpleMain _ -> do putStrLn "Invalid input."; schedulerSimpleMain main :: IO() main = do putStr "What is the name of the schedule? " sName <- getLine schedulerSimpleMain (initializeFile sName) Thanks, and apologies if this isn't the correct place to be asking such a question.

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• Why does limiting my virtual memory to 512MB with ulimit -v crash the JVM?

  - by Narinder Kumar

  I am trying to enforce maximum memory a program can consume on a Unix system. I thought ulimit -v should do the trick. Here is a sample Java program I have written for testing : import java.util.*; import java.io.*; public class EatMem { public static void main(String[] args) throws IOException, InterruptedException { System.out.println("Starting up..."); System.out.println("Allocating 128 MB of Memory"); List<byte[]> list = new LinkedList<byte[]>(); list.add(new byte[134217728]); //128 MB System.out.println("Done...."); } } By default, my ulimit settings are (output of ulimit -a) : core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 31398 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 31398 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited When I execute my java program (java EatMem), it executes without any problems. Now I try to limit max memory available to any program launched in the current shell to 512MB by launching the following command : ulimit -v 524288 ulimit -a output shows the limit to be set correctly (I suppose): core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 31398 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 31398 virtual memory (kbytes, -v) 524288 file locks (-x) unlimited If I now try to execute my java program, it gives me the following error: Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. Ideally it should not happen as my Java program is only taking around 128MB of memory which is well within my specified ulimit parameters. If I change the arguments to my Java program as below: java -Xmx256m EatMem The program again works fine. While trying to give more memory than limited by ulimit like : java -Xmx800m EatMem results in expected error. Why the program fails to execute in the first case after setting ulimit ? I have tried the above test on Ubuntu 11.10 and 12.0.4 with Java 1.6 and Java 7

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• Diving into OpenStack Network Architecture - Part 2 - Basic Use Cases

  - by Ronen Kofman

    rkofman Normal rkofman 4 138 2014-06-05T03:38:00Z 2014-06-05T05:04:00Z 3 2735 15596 Oracle Corporation 129 36 18295 12.00 Clean Clean false false false false EN-US X-NONE HE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;} In the previous post we reviewed several network components including Open vSwitch, Network Namespaces, Linux Bridges and veth pairs. In this post we will take three simple use cases and see how those basic components come together to create a complete SDN solution in OpenStack. With those three use cases we will review almost the entire network setup and see how all the pieces work together. The use cases we will use are: 1.       Create network – what happens when we create network and how can we create multiple isolated networks 2.       Launch a VM – once we have networks we can launch VMs and connect them to networks. 3.       DHCP request from a VM – OpenStack can automatically assign IP addresses to VMs. This is done through local DHCP service controlled by OpenStack Neutron. We will see how this service runs and how does a DHCP request and response look like. In this post we will show connectivity, we will see how packets get from point A to point B. We first focus on how a configured deployment looks like and only later we will discuss how and when the configuration is created. Personally I found it very valuable to see the actual interfaces and how they connect to each other through examples and hands on experiments. After the end game is clear and we know how the connectivity works, in a later post, we will take a step back and explain how Neutron configures the components to be able to provide such connectivity.  We are going to get pretty technical shortly and I recommend trying these examples on your own deployment or using the Oracle OpenStack Tech Preview. Understanding these three use cases thoroughly and how to look at them will be very helpful when trying to debug a deployment in case something does not work. Use case #1: Create Network Create network is a simple operation it can be performed from the GUI or command line. When we create a network in OpenStack the network is only available to the tenant who created it or it could be defined as “shared” and then it can be used by all tenants. A network can have multiple subnets but for this demonstration purpose and for simplicity we will assume that each network has exactly one subnet. Creating a network from the command line will look like this: # neutron net-create net1 Created a new network: +---------------------------+--------------------------------------+ | Field                     | Value                                | +---------------------------+--------------------------------------+ | admin_state_up            | True                                 | | id                        | 5f833617-6179-4797-b7c0-7d420d84040c | | name                      | net1                                 | | provider:network_type     | vlan                                 | | provider:physical_network | default                              | | provider:segmentation_id  | 1000                                 | | shared                    | False                                | | status                    | ACTIVE                               | | subnets                   |                                      | | tenant_id                 | 9796e5145ee546508939cd49ad59d51f     | +---------------------------+--------------------------------------+ Creating a subnet for this network will look like this: # neutron subnet-create net1 10.10.10.0/24 Created a new subnet: +------------------+------------------------------------------------+ | Field            | Value                                          | +------------------+------------------------------------------------+ | allocation_pools | {"start": "10.10.10.2", "end": "10.10.10.254"} | | cidr             | 10.10.10.0/24                                  | | dns_nameservers  |                                                | | enable_dhcp      | True                                           | | gateway_ip       | 10.10.10.1                                     | | host_routes      |                                                | | id               | 2d7a0a58-0674-439a-ad23-d6471aaae9bc           | | ip_version       | 4                                              | | name             |                                                | | network_id       | 5f833617-6179-4797-b7c0-7d420d84040c           | | tenant_id        | 9796e5145ee546508939cd49ad59d51f               | +------------------+------------------------------------------------+ We now have a network and a subnet, on the network topology view this looks like this: Now let’s dive in and see what happened under the hood. Looking at the control node we will discover that a new namespace was created: # ip netns list qdhcp-5f833617-6179-4797-b7c0-7d420d84040c   The name of the namespace is qdhcp-<network id> (see above), let’s look into the namespace and see what’s in it: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00     inet 127.0.0.1/8 scope host lo     inet6 ::1/128 scope host        valid_lft forever preferred_lft forever 12: tap26c9b807-7c: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN     link/ether fa:16:3e:1d:5c:81 brd ff:ff:ff:ff:ff:ff     inet 10.10.10.3/24 brd 10.10.10.255 scope global tap26c9b807-7c     inet6 fe80::f816:3eff:fe1d:5c81/64 scope link        valid_lft forever preferred_lft forever   We see two interfaces in the namespace, one is the loopback and the other one is an interface called “tap26c9b807-7c”. This interface has the IP address of 10.10.10.3 and it will also serve dhcp requests in a way we will see later. Let’s trace the connectivity of the “tap26c9b807-7c” interface from the namespace.  First stop is OVS, we see that the interface connects to bridge  “br-int” on OVS: # ovs-vsctl show 8a069c7c-ea05-4375-93e2-b9fc9e4b3ca1     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-ex         Port br-ex             Interface br-ex                 type: internal     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port "tap26c9b807-7c"             tag: 1             Interface "tap26c9b807-7c"                 type: internal         Port br-int             Interface br-int                 type: internal     ovs_version: "1.11.0"   In the picture above we have a veth pair which has two ends called “int-br-eth2” and "phy-br-eth2", this veth pair is used to connect two bridge in OVS "br-eth2" and "br-int". In the previous post we explained how to check the veth connectivity using the ethtool command. It shows that the two are indeed a pair: # ethtool -S int-br-eth2 NIC statistics:      peer_ifindex: 10 . .   #ip link . . 10: phy-br-eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 . . Note that “phy-br-eth2” is connected to a bridge called "br-eth2" and one of this bridge's interfaces is the physical link eth2. This means that the network which we have just created has created a namespace which is connected to the physical interface eth2. eth2 is the “VM network” the physical interface where all the virtual machines connect to where all the VMs are connected. About network isolation: OpenStack supports creation of multiple isolated networks and can use several mechanisms to isolate the networks from one another. The isolation mechanism can be VLANs, VxLANs or GRE tunnels, this is configured as part of the initial setup in our deployment we use VLANs. When using VLAN tagging as an isolation mechanism a VLAN tag is allocated by Neutron from a pre-defined VLAN tags pool and assigned to the newly created network. By provisioning VLAN tags to the networks Neutron allows creation of multiple isolated networks on the same physical link.  The big difference between this and other platforms is that the user does not have to deal with allocating and managing VLANs to networks. The VLAN allocation and provisioning is handled by Neutron which keeps track of the VLAN tags, and responsible for allocating and reclaiming VLAN tags. In the example above net1 has the VLAN tag 1000, this means that whenever a VM is created and connected to this network the packets from that VM will have to be tagged with VLAN tag 1000 to go on this particular network. This is true for namespace as well, if we would like to connect a namespace to a particular network we have to make sure that the packets to and from the namespace are correctly tagged when they reach the VM network. In the example above we see that the namespace interface “tap26c9b807-7c” has vlan tag 1 assigned to it, if we examine OVS we see that it has flows which modify VLAN tag 1 to VLAN tag 1000 when a packet goes to the VM network on eth2 and vice versa. We can see this using the dump-flows command on OVS for packets going to the VM network we see the modification done on br-eth2: #  ovs-ofctl dump-flows br-eth2 NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18669.401s, table=0, n_packets=857, n_bytes=163350, idle_age=25, priority=4,in_port=2,dl_vlan=1 actions=mod_vlan_vid:1000,NORMAL  cookie=0x0, duration=165108.226s, table=0, n_packets=14, n_bytes=1000, idle_age=5343, hard_age=65534, priority=2,in_port=2 actions=drop  cookie=0x0, duration=165109.813s, table=0, n_packets=1671, n_bytes=213304, idle_age=25, hard_age=65534, priority=1 actions=NORMAL   For packets coming from the interface to the namespace we see the following modification: #  ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18690.876s, table=0, n_packets=1610, n_bytes=210752, idle_age=1, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL  cookie=0x0, duration=165130.01s, table=0, n_packets=75, n_bytes=3686, idle_age=4212, hard_age=65534, priority=2,in_port=1 actions=drop  cookie=0x0, duration=165131.96s, table=0, n_packets=863, n_bytes=160727, idle_age=1, hard_age=65534, priority=1 actions=NORMAL   To summarize we can see that when a user creates a network Neutron creates a namespace and this namespace is connected through OVS to the “VM network”. OVS also takes care of tagging the packets from the namespace to the VM network with the correct VLAN tag and knows to modify the VLAN for packets coming from VM network to the namespace. Now let’s see what happens when a VM is launched and how it is connected to the “VM network”. Use case #2: Launch a VM Launching a VM can be done from Horizon or from the command line this is how we do it from Horizon: Attach the network: And Launch Once the virtual machine is up and running we can see the associated IP using the nova list command : # nova list +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | ID                                   | Name         | Status | Task State | Power State | Networks        | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | 3707ac87-4f5d-4349-b7ed-3a673f55e5e1 | Oracle Linux | ACTIVE | None       | Running     | net1=10.10.10.2 | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ The nova list command shows us that the VM is running and that the IP 10.10.10.2 is assigned to this VM. Let’s trace the connectivity from the VM to VM network on eth2 starting with the VM definition file. The configuration files of the VM including the virtual disk(s), in case of ephemeral storage, are stored on the compute node at/var/lib/nova/instances/<instance-id>/. Looking into the VM definition file ,libvirt.xml,  we see that the VM is connected to an interface called “tap53903a95-82” which is connected to a Linux bridge called “qbr53903a95-82”: <interface type="bridge">       <mac address="fa:16:3e:fe:c7:87"/>       <source bridge="qbr53903a95-82"/>       <target dev="tap53903a95-82"/>     </interface>   Looking at the bridge using the brctl show command we see this: # brctl show bridge name     bridge id               STP enabled     interfaces qbr53903a95-82          8000.7e7f3282b836       no              qvb53903a95-82                                                         tap53903a95-82    The bridge has two interfaces, one connected to the VM (“tap53903a95-82 “) and another one ( “qvb53903a95-82”) connected to “br-int” bridge on OVS: # ovs-vsctl show 83c42f80-77e9-46c8-8560-7697d76de51c     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-int         Port br-int             Interface br-int                 type: internal         Port "int-br-eth2"             Interface "int-br-eth2"         Port "qvo53903a95-82"             tag: 3             Interface "qvo53903a95-82"     ovs_version: "1.11.0"   As we showed earlier “br-int” is connected to “br-eth2” on OVS using the veth pair int-br-eth2,phy-br-eth2 and br-eth2 is connected to the physical interface eth2. The whole flow end to end looks like this: VM è tap53903a95-82 (virtual interface)è qbr53903a95-82 (Linux bridge) è qvb53903a95-82 (interface connected from Linux bridge to OVS bridge br-int) è int-br-eth2 (veth one end) è phy-br-eth2 (veth the other end) è eth2 physical interface. The purpose of the Linux Bridge connecting to the VM is to allow security group enforcement with iptables. Security groups are enforced at the edge point which are the interface of the VM, since iptables nnot be applied to OVS bridges we use Linux bridge to apply them. In the future we hope to see this Linux Bridge going away rules.  VLAN tags: As we discussed in the first use case net1 is using VLAN tag 1000, looking at OVS above we see that qvo41f1ebcf-7c is tagged with VLAN tag 3. The modification from VLAN tag 3 to 1000 as we go to the physical network is done by OVS  as part of the packet flow of br-eth2 in the same way we showed before. To summarize, when a VM is launched it is connected to the VM network through a chain of elements as described here. During the packet from VM to the network and back the VLAN tag is modified. Use case #3: Serving a DHCP request coming from the virtual machine In the previous use cases we have shown that both the namespace called dhcp-<some id> and the VM end up connecting to the physical interface eth2  on their respective nodes, both will tag their packets with VLAN tag 1000.We saw that the namespace has an interface with IP of 10.10.10.3. Since the VM and the namespace are connected to each other and have interfaces on the same subnet they can ping each other, in this picture we see a ping from the VM which was assigned 10.10.10.2 to the namespace: The fact that they are connected and can ping each other can become very handy when something doesn’t work right and we need to isolate the problem. In such case knowing that we should be able to ping from the VM to the namespace and back can be used to trace the disconnect using tcpdump or other monitoring tools. To serve DHCP requests coming from VMs on the network Neutron uses a Linux tool called “dnsmasq”,this is a lightweight DNS and DHCP service you can read more about it here. If we look at the dnsmasq on the control node with the ps command we see this: dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tap26c9b807-7c --except-interface=lo --pid-file=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host --dhcp-optsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/opts --leasefile-ro --dhcp-range=tag0,10.10.10.0,static,120s --dhcp-lease-max=256 --conf-file= --domain=openstacklocal The service connects to the tap interface in the namespace (“--interface=tap26c9b807-7c”), If we look at the hosts file we see this: # cat  /var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host fa:16:3e:fe:c7:87,host-10-10-10-2.openstacklocal,10.10.10.2   If you look at the console output above you can see the MAC address fa:16:3e:fe:c7:87 which is the VM MAC. This MAC address is mapped to IP 10.10.10.2 and so when a DHCP request comes with this MAC dnsmasq will return the 10.10.10.2.If we look into the namespace at the time we initiate a DHCP request from the VM (this can be done by simply restarting the network service in the VM) we see the following: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c tcpdump -n 19:27:12.191280 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from fa:16:3e:fe:c7:87, length 310 19:27:12.191666 IP 10.10.10.3.bootps > 10.10.10.2.bootpc: BOOTP/DHCP, Reply, length 325   To summarize, the DHCP service is handled by dnsmasq which is configured by Neutron to listen to the interface in the DHCP namespace. Neutron also configures dnsmasq with the combination of MAC and IP so when a DHCP request comes along it will receive the assigned IP. Summary In this post we relied on the components described in the previous post and saw how network connectivity is achieved using three simple use cases. These use cases gave a good view of the entire network stack and helped understand how an end to end connection is being made between a VM on a compute node and the DHCP namespace on the control node. One conclusion we can draw from what we saw here is that if we launch a VM and it is able to perform a DHCP request and receive a correct IP then there is reason to believe that the network is working as expected. We saw that a packet has to travel through a long list of components before reaching its destination and if it has done so successfully this means that many components are functioning properly. In the next post we will look at some more sophisticated services Neutron supports and see how they work. We will see that while there are some more components involved for the most part the concepts are the same. @RonenKofman

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• rsync on QNAP NAS fails recently

  - by user192702

  I have been using rsync to copy a large backup file from a remote host to my QNAP NAS. It's been working fine until recently. It seems like almost every time when it executes it's giving a time out after 15s. Following is what I have captured in the log. Any ideas? 2013-11-10 23:10:01 HKT - Executing: rsync -t -v -e ssh [email protected]:/home/backup/backup/backup_file-11102013* /share/homes/backup/backup/web/database [receiver] io timeout after 10 seconds -- exiting rsync error: timeout in data send/receive (code 30) at io.c(140) [receiver=3.0.7] rsync: connection unexpectedly closed (73 bytes received so far) [generator] rsync error: error in rsync protocol data stream (code 12) at io.c(601) [generator=3.0.7] 2013-11-10 23:10:15 HKT - Done rsync

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• What does 'Highest active time' for disk activity in Windows resource monitor mean?

  - by Nick R

  I know what the disk io, disk queue length and other measures are, but what does 'Highest active time' mean? Is it the amount of time it is busy handling requests, or something else? When it is high, does it mean the CPU is busy doing some IO work, or is it just indicating that the disk is busy handling requests? I'm trying to work out if 50% active time means that 50% of the time the disk is either seeking, reading or writing, rather than the kernel is spending 50% of it's time servicing IO requests. Edit Another quick data point here. If you look at the difference between an SSD and a physical disk, the SSD has significantly less activity, so I guess this really means the amount of time the operating system is waiting for the disk to respond and returning data.

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• PHP/Java bridge problem

  - by Jack

  I am using tomcat 6 on windows. Here is the code I am testing. import java.io.ByteArrayOutputStream; import java.io.Closeable; import java.io.StringReader; import javax.script.Invocable; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; /** * Create and run THREAD_COUNT PHP threads, concurrently accessing a * shared resource. * * Create 5 script engines, passing each a shared resource allocated * from Java. Each script engine has to implement Runnable. * * Java accesses the Runnable script engine using * scriptEngine.getInterface() and calls thread.start() to invoke each * PHP Runnable implementations concurrently. */ class PhpThreads { public static final String runnable = new String("<?php\n" + "function run() {\n" + " $out = java_context()->getAttribute('sharedResource', 100);\n" + " $nr = (string)java_context()->getAttribute('nr', 100);\n" + " echo \"started thread: $nr\n\";\n" + " for($i=0; $i<100; $i++) {\n" + " $out->write(ord($nr));\n" + " java('java.lang.Thread')->sleep(1);\n" + " }\n" + "}\n" + "?>\n"); static final int THREAD_COUNT = 5; public static void main(String[] args) throws Exception { ScriptEngineManager manager = new ScriptEngineManager(); Thread threads[] = new Thread[THREAD_COUNT]; ScriptEngine engines[] = new ScriptEngine[THREAD_COUNT]; ByteArrayOutputStream sharedResource = new ByteArrayOutputStream(); StringReader runnableReader = new StringReader(runnable); // create THREAD_COUNT PHP threads for (int i=0; i<THREAD_COUNT; i++) { engines[i] = manager.getEngineByName("php-invocable"); if (engines[i] == null) throw new NullPointerException ("php script engine not found"); engines[i].put("nr", new Integer(i+1)); engines[i].put("sharedResource", sharedResource); engines[i].eval(runnableReader); runnableReader.reset(); // cast the whole script to Runnable; note also getInterface(specificClosure, type) Runnable r = (Runnable) ((Invocable)engines[i]).getInterface(Runnable.class); threads[i] = new Thread(r); } // run the THREAD_COUNT PHP threads for (int i=0; i<THREAD_COUNT; i++) { threads[i].start(); } // wait for the THREAD_COUNT PHP threads to finish for (int i=0; i<THREAD_COUNT; i++) { threads[i].join(); ((Closeable)engines[i]).close(); } // print the output generated by the THREAD_COUNT concurrent threads String result = sharedResource.toString(); System.out.println(result); // Check result Object res=manager.getEngineByName("php").eval( "<?php " + "exit((int)('10011002100310041005'!=" + "@system(\"echo -n "+result+"|sed 's/./&\\\n/g'|sort|uniq -c|tr -d ' \\\n'\")));" + "?>"); System.exit(((Number)res).intValue()); } } I have added all the libraries. When I run the file I get the following error - run: Exception in thread "main" javax.script.ScriptException: java.io.IOException: Cannot run program "php-cgi": CreateProcess error=2, The system cannot find the file specified at php.java.script.InvocablePhpScriptEngine.eval(InvocablePhpScriptEngine.java:209) at php.java.script.SimplePhpScriptEngine.eval(SimplePhpScriptEngine.java:178) at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:232) at PhpThreads.main(NewClass.java:53) Caused by: java.io.IOException: Cannot run program "php-cgi": CreateProcess error=2, The system cannot find the file specified at java.lang.ProcessBuilder.start(ProcessBuilder.java:459) at java.lang.Runtime.exec(Runtime.java:593) at php.java.bridge.Util$Process.start(Util.java:1064) at php.java.bridge.Util$ProcessWithErrorHandler.start(Util.java:1166) at php.java.bridge.Util$ProcessWithErrorHandler.start(Util.java:1217) at php.java.script.CGIRunner.doRun(CGIRunner.java:126) at php.java.script.HttpProxy.doRun(HttpProxy.java:63) at php.java.script.CGIRunner.run(CGIRunner.java:111) at php.java.bridge.ThreadPool$Delegate.run(ThreadPool.java:60) Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified at java.lang.ProcessImpl.create(Native Method) at java.lang.ProcessImpl.<init>(ProcessImpl.java:81) at java.lang.ProcessImpl.start(ProcessImpl.java:30) at java.lang.ProcessBuilder.start(ProcessBuilder.java:452) ... 8 more What am I missing?

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• Debian apt dependency mismatch (libc6)

  - by Sean Gordon

  Earlier, I tried to install package via apt-get (cython), but it failed with the Errors were encountered while processing: message, and since then, apt is refusing to install anything. apt-get check output below: root@dix:~# apt-get check Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies: libc6 : Depends: libc-bin (= 2.11.3-2) but 2.11.3-4 is installed libc6-dev : Depends: libc6 (= 2.11.3-4) but 2.11.3-2 is installed libc6-i386 : Depends: libc6 (= 2.11.3-4) but 2.11.3-2 is installed E: Unmet dependencies. Try using -f. Apt/aptitude don't seem to be able to fix this dependency issue, and I don't know what to do. Edit: Running apt-get -f install results in no change, and my sources are all squeeze. Running apt-get update then apt-get dist-upgrade show no change either. Edit 2: I went back to try this again in a new terminal and apt-get -f install gives this error: dpkg: error processing /var/cache/apt/archives/libc6_2.11.3-4_amd64.deb (--unpack): subprocess new pre-installation script killed by signal (Aborted) configured to not write apport reports Errors were encountered while processing: /var/cache/apt/archives/libc6_2.11.3-4_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) Edit 3: Using apt-get clean first, then the previous commands, results in the first error again. Using apt-get -f dist-upgrade gives the below. Reading package lists... Building dependency tree... Reading state information... Correcting dependencies... Done The following packages will be upgraded: apache2 apache2-mpm-prefork apache2-utils apache2.2-bin apache2.2-common at automake base-files bind9 bind9-doc bind9-host bind9utils debian-archive-keyring dnsutils dpkg-dev file host initscripts isc-dhcp-client isc-dhcp-common krb5-multidev libapr1 libbind9-60 libc6 libdns69 libdpkg-perl libexpat1 libexpat1-dev libgc1c2 libgssapi-krb5-2 libgssrpc4 libisc62 libisccc60 libisccfg62 libk5crypto3 libkadm5clnt-mit7 libkadm5srv-mit7 libkdb5-4 libkrb5-3 libkrb5-dev libkrb5support0 liblwres60 libmagic1 libmysqlclient16 libnss3-1d libssl-dev libssl0.9.8 libtiff4 libtiff4-dev libtiffxx0c2 libxi6 libxml2 linux-libc-dev lwresd mysql-client-5.1 mysql-common mysql-server mysql-server-5.1 mysql-server-core-5.1 openjdk-6-jre openjdk-6-jre-headless openjdk-6-jre-lib openssh-client openssh-server openssl procps python python-crypto python-minimal sudo sysv-rc sysvinit sysvinit-utils tzdata tzdata-java 75 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 5 not fully installed or removed. Need to get 0 B/79.9 MB of archives. After this operation, 1,411 kB of additional disk space will be used. (Reading database ... 52241 files and directories currently installed.) Preparing to replace libc6 2.11.3-2 (using .../libc6_2.11.3-4_amd64.deb) ... *** stack smashing detected ***: /usr/bin/perl terminated ======= Backtrace: ========= /lib/libc.so.6(__fortify_fail+0x37)[0x7fdaad9b9f87] /lib/libc.so.6(__fortify_fail+0x0)[0x7fdaad9b9f50] /usr/lib/libperl.so.5.10(Perl_yylex+0x5896)[0x7fdaae343346] [0x8e83a0] ======= Memory map: ======== 00400000-00402000 r-xp 00000000 08:01 525338 /usr/bin/perl 00601000-00602000 rw-p 00001000 08:01 525338 /usr/bin/perl 00602000-0091f000 rw-p 00000000 00:00 0 [heap] 7fdaaca54000-7fdaaca6a000 r-xp 00000000 08:01 393818 /lib/libgcc_s.so.1 7fdaaca6a000-7fdaacc69000 ---p 00016000 08:01 393818 /lib/libgcc_s.so.1 7fdaacc69000-7fdaacc6a000 rw-p 00015000 08:01 393818 /lib/libgcc_s.so.1 7fdaacc6a000-7fdaacc6f000 r-xp 00000000 08:01 524949 /usr/lib/perl5/auto/Locale/gettext/gettext.so 7fdaacc6f000-7fdaace6e000 ---p 00005000 08:01 524949 /usr/lib/perl5/auto/Locale/gettext/gettext.so 7fdaace6e000-7fdaace6f000 rw-p 00004000 08:01 524949 /usr/lib/perl5/auto/Locale/gettext/gettext.so 7fdaace6f000-7fdaace79000 r-xp 00000000 08:01 532753 /usr/lib/perl/5.10.1/auto/Encode/Encode.so 7fdaace79000-7fdaad078000 ---p 0000a000 08:01 532753 /usr/lib/perl/5.10.1/auto/Encode/Encode.so 7fdaad078000-7fdaad079000 rw-p 00009000 08:01 532753 /usr/lib/perl/5.10.1/auto/Encode/Encode.so 7fdaad079000-7fdaad07e000 r-xp 00000000 08:01 525444 /usr/lib/perl/5.10.1/auto/IO/IO.so 7fdaad07e000-7fdaad27d000 ---p 00005000 08:01 525444 /usr/lib/perl/5.10.1/auto/IO/IO.so 7fdaad27d000-7fdaad27e000 rw-p 00004000 08:01 525444 /usr/lib/perl/5.10.1/auto/IO/IO.so 7fdaad27e000-7fdaad299000 r-xp 00000000 08:01 525450 /usr/lib/perl/5.10.1/auto/POSIX/POSIX.so 7fdaad299000-7fdaad498000 ---p 0001b000 08:01 525450 /usr/lib/perl/5.10.1/auto/POSIX/POSIX.so 7fdaad498000-7fdaad49b000 rw-p 0001a000 08:01 525450 /usr/lib/perl/5.10.1/auto/POSIX/POSIX.so 7fdaad49b000-7fdaad49e000 r-xp 00000000 08:01 525436 /usr/lib/perl/5.10.1/auto/Fcntl/Fcntl.so 7fdaad49e000-7fdaad69e000 ---p 00003000 08:01 525436 /usr/lib/perl/5.10.1/auto/Fcntl/Fcntl.so 7fdaad69e000-7fdaad69f000 rw-p 00003000 08:01 525436 /usr/lib/perl/5.10.1/auto/Fcntl/Fcntl.so 7fdaad69f000-7fdaad6a7000 r-xp 00000000 08:01 393824 /lib/libcrypt-2.11.3.so 7fdaad6a7000-7fdaad8a6000 ---p 00008000 08:01 393824 /lib/libcrypt-2.11.3.so 7fdaad8a6000-7fdaad8a7000 r--p 00007000 08:01 393824 /lib/libcrypt-2.11.3.so 7fdaad8a7000-7fdaad8a8000 rw-p 00008000 08:01 393824 /lib/libcrypt-2.11.3.so 7fdaad8a8000-7fdaad8d6000 rw-p 00000000 00:00 0 7fdaad8d6000-7fdaada2f000 r-xp 00000000 08:01 393822 /lib/libc-2.11.3.so 7fdaada2f000-7fdaadc2e000 ---p 00159000 08:01 393822 /lib/libc-2.11.3.so 7fdaadc2e000-7fdaadc32000 r--p 00158000 08:01 393822 /lib/libc-2.11.3.so 7fdaadc32000-7fdaadc33000 rw-p 0015c000 08:01 393822 /lib/libc-2.11.3.so 7fdaadc33000-7fdaadc38000 rw-p 00000000 00:00 0 7fdaadc38000-7fdaadc4f000 r-xp 00000000 08:01 393248 /lib/libpthread-2.11.3.so 7fdaadc4f000-7fdaade4e000 ---p 00017000 08:01 393248 /lib/libpthread-2.11.3.so 7fdaade4e000-7fdaade4f000 r--p 00016000 08:01 393248 /lib/libpthread-2.11.3.so 7fdaade4f000-7fdaade50000 rw-p 00017000 08:01 393248 /lib/libpthread-2.11.3.so 7fdaade50000-7fdaade54000 rw-p 00000000 00:00 0 7fdaade54000-7fdaaded4000 r-xp 00000000 08:01 393826 /lib/libm-2.11.3.so 7fdaaded4000-7fdaae0d4000 ---p 00080000 08:01 393826 /lib/libm-2.11.3.so 7fdaae0d4000-7fdaae0d5000 r--p 00080000 08:01 393826 /lib/libm-2.11.3.so 7fdaae0d5000-7fdaae0d6000 rw-p 00081000 08:01 393826 /lib/libm-2.11.3.so 7fdaae0d6000-7fdaae0d8000 r-xp 00000000 08:01 393825 /lib/libdl-2.11.3.so 7fdaae0d8000-7fdaae2d8000 ---p 00002000 08:01 393825 /lib/libdl-2.11.3.so 7fdaae2d8000-7fdaae2d9000 r--p 00002000 08:01 393825 /lib/libdl-2.11.3.so 7fdaae2d9000-7fdaae2da000 rw-p 00003000 08:01 393825 /lib/libdl-2.11.3.so 7fdaae2da000-7fdaae43f000 r-xp 00000000 08:01 525387 /usr/lib/libperl.so.5.10.1 7fdaae43f000-7fdaae63e000 ---p 00165000 08:01 525387 /usr/lib/libperl.so.5.10.1 7fdaae63e000-7fdaae647000 rw-p 00164000 08:01 525387 /usr/lib/libperl.so.5.10.1 7fdaae647000-7fdaae665000 r-xp 00000000 08:01 393819 /lib/ld-2.11.3.so 7fdaae854000-7fdaae859000 rw-p 00000000 00:00 0 7fdaae862000-7fdaae864000 rw-p 00000000 00:00 0 7fdaae864000-7fdaae865000 r--p 0001d000 08:01 393819 /lib/ld-2.11.3.so 7fdaae865000-7fdaae866000 rw-p 0001e000 08:01 393819 /lib/ld-2.11.3.so 7fdaae866000-7fdaae867000 rw-p 00000000 00:00 0 7fff9616d000-7fff9618e000 rw-p 00000000 00:00 0 [stack] 7fff961ff000-7fff96200000 r-xp 00000000 00:00 0 [vdso] ffffffffff600000-ffffffffff601000 r--p 00000000 00:00 0 [vsyscall] dpkg: error processing /var/cache/apt/archives/libc6_2.11.3-4_amd64.deb (--unpack): subprocess new pre-installation script killed by signal (Aborted) Errors were encountered while processing: /var/cache/apt/archives/libc6_2.11.3-4_amd64.deb

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• Playing an Online mp3

  - by Mohsen

  I have a problem with playing online mp3s. I'm using latest version of javazoom's jlayer and basicplayer. Here is the exception: Caused by: javazoom.jlgui.basicplayer.BasicPlayerException: java.io.EOFException at javazoom.jlgui.basicplayer.BasicPlayer.initAudioInputStream(Unknown Source) at javazoom.jlgui.basicplayer.BasicPlayer.open(Unknown Source) ... 12 more Caused by: java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at com.sun.media.sound.WaveFileReader.getFMT(WaveFileReader.java:244) at com.sun.media.sound.WaveFileReader.getAudioFileFormat(WaveFileReader.java:85) at javax.sound.sampled.AudioSystem.getAudioFileFormat(AudioSystem.java:985) at javazoom.jlgui.basicplayer.BasicPlayer.initAudioInputStream(Unknown Source) ... 15 more My java is 1.6.0_16. Certain files cannot be player through the Internet. I have a set of mp3s, playing one after the other. Randomly one mp3 doesn't work throwing above exception. Some mp3s can be played by calling again play() method if javazoom's basicplayer, but others can never be played online. I was able to find this post but I doubt if this really relates to my directx version or something. Mohsen

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• Algorithm to calculate a page importance based on its views / comments

  - by stacker

  I need an algorithm that allows me to determine an appropriate <priority> field for my website's sitemap based on the page's views and comments count. For those of you unfamiliar with sitemaps, the priority field is used to signal the importance of a page relative to the others on the same website. It must be a decimal number between 0 and 1. The algorithm will accept two parameters, viewCount and commentCount, and will return the priority value. For example: GetPriority(100000, 100000); // Damn, a lot of views/comments! The returned value will be very close to 1, for example 0.995 GetPriority(3, 2); // Ok not many users are interested in this page, so for example it will return 0.082

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• please explain my fio results - is O_SYNC|O_DIRECT misbehaving on linux?

  - by Zoltan

  I'm going mad over figuring out what the problem could be with one of our storage boxes. With a simple fio script I'm testing random writes using bs=1M and direct=1. The SSD is a Samsung 840pro attached to an LSI HBA (3Gbit/s ports). This is the result I'm getting under FreeBSD 9.1: WRITE: io=13169MB, aggrb=224743KB/s, minb=224743KB/s, maxb=224743KB/s, mint=60002msec, maxt=60002msec This is regardless of sync being set to 0 or 1. On linux, this is the result with sync=0: WRITE: io=14828MB, aggrb=253060KB/s, minb=253060KB/s, maxb=253060KB/s, mint=60001msec, maxt=60001msec and with sync=1: WRITE: io=6360.0MB, aggrb=108542KB/s, minb=108542KB/s, maxb=108542KB/s, mint=60001msec, maxt=60001msec My understanding is that since I'm operating on the raw block device, O_SYNC should not make any difference - there's no filesystem, any barrier, anything between the writes and the drive itself. Especially with O_DIRECT|O_SYNC set. Any ideas? For reference, here's the fio script I'm testing with: [global] bs=1M ioengine=sync iodepth=4 size=16g direct=1 runtime=60 filename=/dev/sdh sync=1 [rand-write] rw=randwrite stonewall

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• How to get "all" (or the MAIN/LAUNCHER) android intent

  - by Christoph Jerolimov

  Hey, i want receive all start app intents (i think MAIN/LAUNCHER, see below) to log how often i used the application. So i do not want create an activity... I tried several receiver blocks, but for now nothing works: with, without priority, only the action, both, only the category and so on.. <receiver android:name=".Receiver" android:enabled="true" android:process=".e"> <intent-filter priority="100000" android:priority="100000"> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </receiver> Have anyone an idea? Thanks

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• Implement OAuth in Java

  - by phineas

  I made an an attempt to implement OAuth for my programming idea in Java, but I failed miserably. I don't know why, but my code doesn't work. Every time I run my program, an IOException is thrown with the reason "java.io.IOException: Server returned HTTP response code: 401" (401 means Unauthorized). I had a close look at the docs, but I really don't understand why it doesn't work. My OAuth provider I wanted to use is twitter, where I've registered my app, too. Thanks in advance phineas OAuth docs Twitter API wiki Class Base64Coder import java.io.InputStreamReader; import java.io.BufferedReader; import java.io.OutputStream; import java.io.IOException; import java.io.UnsupportedEncodingException; import java.net.URL; import java.net.URLEncoder; import java.net.URLConnection; import java.net.MalformedURLException; import javax.crypto.Mac; import javax.crypto.spec.SecretKeySpec; import java.security.NoSuchAlgorithmException; import java.security.InvalidKeyException; public class Request { public static String read(String url) { StringBuffer buffer = new StringBuffer(); try { /** * get the time - note: value below zero * the millisecond value is used for oauth_nonce later on */ int millis = (int) System.currentTimeMillis() * -1; int time = (int) millis / 1000; /** * Listing of all parameters necessary to retrieve a token * (sorted lexicographically as demanded) */ String[][] data = { {"oauth_callback", "SOME_URL"}, {"oauth_consumer_key", "MY_CONSUMER_KEY"}, {"oauth_nonce", String.valueOf(millis)}, {"oauth_signature", ""}, {"oauth_signature_method", "HMAC-SHA1"}, {"oauth_timestamp", String.valueOf(time)}, {"oauth_version", "1.0"} }; /** * Generation of the signature base string */ String signature_base_string = "POST&"+URLEncoder.encode(url, "UTF-8")+"&"; for(int i = 0; i < data.length; i++) { // ignore the empty oauth_signature field if(i != 3) { signature_base_string += URLEncoder.encode(data[i][0], "UTF-8") + "%3D" + URLEncoder.encode(data[i][1], "UTF-8") + "%26"; } } // cut the last appended %26 signature_base_string = signature_base_string.substring(0, signature_base_string.length()-3); /** * Sign the request */ Mac m = Mac.getInstance("HmacSHA1"); m.init(new SecretKeySpec("CONSUMER_SECRET".getBytes(), "HmacSHA1")); m.update(signature_base_string.getBytes()); byte[] res = m.doFinal(); String sig = String.valueOf(Base64Coder.encode(res)); data[3][1] = sig; /** * Create the header for the request */ String header = "OAuth "; for(String[] item : data) { header += item[0]+"=\""+item[1]+"\", "; } // cut off last appended comma header = header.substring(0, header.length()-2); System.out.println("Signature Base String: "+signature_base_string); System.out.println("Authorization Header: "+header); System.out.println("Signature: "+sig); String charset = "UTF-8"; URLConnection connection = new URL(url).openConnection(); connection.setDoInput(true); connection.setDoOutput(true); connection.setRequestProperty("Accept-Charset", charset); connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=" + charset); connection.setRequestProperty("Authorization", header); connection.setRequestProperty("User-Agent", "XXXX"); OutputStream output = connection.getOutputStream(); output.write(header.getBytes(charset)); BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream())); String read; while((read = reader.readLine()) != null) { buffer.append(read); } } catch(Exception e) { e.printStackTrace(); } return buffer.toString(); } public static void main(String[] args) { System.out.println(Request.read("http://api.twitter.com/oauth/request_token")); } }

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• How to calculate a RTOS task's time

  - by Adnan

  Hello all, I have written a code in c for Arm7 using RTOS. There are multiple tasks who's priority is set to same level. So the tasks executes on round-robin base. There is an exception that one task (Default) has set to lower priority then the other task in rtos. So that if no task is running, the default or lower priority task runs. Now i want to calculate the exact total timing (time duration) for that default task runs. Can any one give some idea what to do .... and how to do in code.. Regards Dani

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• MDX Filter a dimention with another dimension

  - by John Hartsock

  To all excuse my ignorance, but im new to MDX below is the query im trying to run SELECT NON EMPTY { [Measures].[Task Burn Down] } ON COLUMNS, NON EMPTY { ([Calendar].[Date].[Date].ALLMEMBERS * [Priority].[Priority Code].[Priority Code].ALLMEMBERS ) } DIMENSION PROPERTIES MEMBER_CAPTION, MEMBER_UNIQUE_NAME ON ROWS FROM ( SELECT ( { Filter([Calendar].[Date].AllMembers, [Calendar].[Date].CurrentMember <= [Sprint].[Sprint].CurrentMember.Properties("Stop Date")) } ) ON COLUMNS FROM ( SELECT ( { [Sprint].[Sprint].AllMembers } ) ON COLUMNS FROM ( SELECT ( { [Team].[Team].AllMembers } ) ON COLUMNS FROM [Backlog2] ) ) ) WHERE ( [Team].[Team].&[27], [Sprint].[Sprint].&[9] ) CELL PROPERTIES VALUE, BACK_COLOR, FORE_COLOR, FORMATTED_VALUE, FORMAT_STRING, FONT_NAME, FONT_SIZE, FONT_FLAGS When I run this I expect to get 1 value for [Measures].[Task Burn Down] for each day of the month. But I only want one month. My Sprint dimension has a stop date and I do not want to return any values after the stop date. What am I doing wrong?

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• Ruby: "do this task eventually"

  - by marienbad

  I hope this question is clear enough -- if not let me know :) What API would I use when I want to write a procedure at runtime and then just run it eventually at low priority while continuing to do the important stuff right now? Example: link checker 1. I write a blog post with links represented by Link objects. I publish the post. 2. Eventually (at very low priority) the system gets around to fetching the URL of each Link object to make sure it's not broken and indicates that in a property of the Link object. 3. When a user visits my blog post, the render code that turns Link objects into HTML knows whether the links have been checked. I'm assuming there's a very general purpose API for doing this kind of "eventually/low priority" stuff.

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• haproxy access list using path_dir having issues with firefox

  - by user11243

  I'm trying to route all requests containing a path directory of /socket.io/ to a separate port with HAProxy. Here is my config file: global maxconn 4096 # Total Max Connections. This is dependent on ulimit nbproc 2 defaults mode http frontend all 0.0.0.0:80 timeout client 86400000 default_backend web_servers acl is_stream path_dir socket.io use_backend stream_servers if is_stream backend web_servers balance roundrobin option forwardfor # This sets X-Forwarded-For timeout server 30000 timeout connect 4000 server web1 127.0.0.1:4000 weight 1 maxconn 1024 check backend stream_servers balance roundrobin option forwardfor # This sets X-Forwarded-For timeout queue 5000 timeout server 86400000 timeout connect 86400000 server stream1 127.0.0.1:5100 weight 1 maxconn 1024 check URL paths with a /socket.io/ get correctly directed to port 5100 in chrome and safari. However not for firefox. I'm running Haproxy locally on my mac for dev, not sure if it has anything to do with it. I'm using haproxy 1.4.8 and Firefox 3.6.15. I've tried clearing cache on firefox and it didn't help, so I'm thinking there's something wrong with the way HAProxy parses through the Firefox request headers.

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• How to get everything in the string, but a particular pattern

  - by José Leal

  Yet another regexp question: I have a string as the following, "This is a string, and I have a priority !1" So I want to build a regexp that extracts my priority, which is this number 1 preceded by the "!". To extract it is very easy, "!([1-4])". But now I want to extract the text, leaving it out! How can I do that? DETAIL: The !1 can be anywhere in the string, so this is also perfectly fine: "This is a string, !1 and I have a priority" Thanks! UPDATE: I'm using scala

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• Keeping DB Table sorted using multi-field formula (Microsoft SQL)

  - by user298167

  Hello Everybody. I have a Job Table which has two interesting columns: Creation Date and Importance (high - 3, medium 2, low - 1). Job's priority calculated like this: Priority = Importance * (time passed since creation). The problem is, Every time I would like to pick 200 jobs with highest priority, I dont want to resort the table. Is there a way to keep rows sorted? I was also thinking about having three tables one for High, Medium and Low and then sort those by Creation Date. Thanks

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• Redis Cookbook Chat Recipe

  - by Tommy Kennedy

  I am a new starter to Node.Js and Redis. I got the Redis cookbook and was trying out the Chat client & Server recipe. I was wondering if anybody got the code to work or if there is some bug in the code. I dont see where the sent messages from the client get invoked on the server. Any help would be great. Regards, Tom Client Code: <?php ?> <html> <head> <title></title> <script src="http://192.168.0.118:8000/socket.io/socket.io.js"></script> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script> <script> var socket = io.connect('192.168.0.118',{port:8000}); socket.on('message', function(data){ alert(data); //var li = new Element('li').insert(data); //$('messages').insert({top: li}); }); </script> </head> <body> <ul id="messages"> <!-- chat messages go here --> </ul> <form id="chatform" action=""> <input id="chattext" type="text" value="" /> <input type="submit" value="Send" /> </form> <script> $('#chatform').submit(function() { socket.emit('message', 'test'); //$('chattext').val()); $('chattext').val(""); // cleanup the field return false; }); </script> </body> </html> Server Code: var http = require('http'); io = require('socket.io'); redis = require('redis'); rc = redis.createClient(); //rc1 = redis.createClient(); rc.on("connect",function(){ rc.subscribe("chat"); console.log("In Chat Stream"); }); rc.on("message",function (channel,message){ console.log("Sending hope: " + message); //rc1.publish("chat","hope"); socketio.sockets.emit('message',message); }); server = http.createServer(function(req,res){ res.writeHead(200,{'content-type':'text/html'}); res.end('<h1>hello world</h1>'); }); server.listen(8000); var socketio = io.listen(server);

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• RSync over SSH hangs and fails with timeout

  - by tx2

  Client: Gentoo, GCC 4.3.4, RSync 3.0.9 Server: Ubuntu 10.04.4 LTS, RSync 3.0.7 Client and server connectet through is Internet, about 2Mbps. Ping is ok. RSync called on any files in any direction hangs on random file, then, after timeout, fails with: [sender] io timeout after 30 seconds -- exiting rsync error: timeout in data send/receive (code 30) at io.c(140) [sender=3.0.9] [sender] _exit_cleanup(code=30, file=io.c, line=140): about to call exit(30) In 1/10 trys is pass correctly. I've tryed to add SSH options TcpRcvBufPoll=yes, KeepAlive=yes; disable and enable rsync compression -- no changes. How can i make rsync works properly?

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• VPS stops responding every now and again

  - by Or W

  I have a Linode vps that I use to host some of my websites on. It's Ubuntu based and it's up to date in terms of all packages. I don't have any cron jobs scheduled or any automatic processes. I host a few (up to date) wordpress blogs there that have very little traffic altogether. Every day (at a different time) my server stops responding, I can't SSH to it, web access is getting timed out and it just dies until I reboot it through the Linode manager. On the linode dashboard I can see that the CPU is not very high (2-3%) Incoming/Outgoing traffic is on 0 and the IO count has a spike just before the server stops responding (SWAP IO is at 2k and IO Rate is at 5k). When I reboot the server everything is just fine. I'm trying to figure out a way to analyze what's going on at these random times where the server freezes up. How can I determine the problem?

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• Nightly backups (and maybe other tasks) causing server alerts

  - by J. Pablo Fernández

  I have two independent alert notification systems for my servers. The server is a virtual machine on Linode and one of the alerts comes from Linode. The other monitoring system we use is New Relic. They are both watching out for IO utilization. Every night I get alerts from both of them as the server is using too much IO. I run quite a few tasks in the middle of the night but the one I confirmed that can cause IO-warnings is running the backups. The backup is done by s3cmd sync. I tried ionice but it still generates the warnings. Getting warnings every night reduces the efficacy of warnings when they happen for real. For Linode I could raise the level at which a warning is issued, but it might mean making the whole thing useless as the level is too high. What would be the proper solution for this?

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• Fixing up Configurations in BizTalk Solution Files

  - by Elton Stoneman

  Just a quick one this, but useful for mature BizTalk solutions, where over time the configuration settings can get confused, meaning Debug configurations building in Release mode, or Deployment configurations building in Development mode. That can cause issues in the build which aren't obvious, so it's good to fix up the configurations. It's time-consuming in VS or in a text editor, so this bit of PowerShell may come in useful - just substitute your own solution path in the $path variable: $path = 'C:\x\y\z\x.y.z.Integration.sln' $backupPath = [System.String]::Format('{0}.bak', $path) [System.IO.File]::Copy($path, $backupPath, $True) $sln = [System.IO.File]::ReadAllText($path)   $sln = $sln.Replace('.Debug|.NET.Build.0 = Deployment|.NET', '.Debug|.NET.Build.0 = Development|.NET') $sln = $sln.Replace('.Debug|.NET.Deploy.0 = Deployment|.NET', '.Debug|.NET.Deploy.0 = Development|.NET') $sln = $sln.Replace('.Debug|Any CPU.ActiveCfg = Deployment|.NET', '.Debug|Any CPU.ActiveCfg = Development|.NET') $sln = $sln.Replace('.Deployment|.NET.ActiveCfg = Debug|Any CPU', '.Deployment|.NET.ActiveCfg = Release|Any CPU') $sln = $sln.Replace('.Deployment|Any CPU.ActiveCfg = Debug|Any CPU', '.Deployment|Any CPU.ActiveCfg = Release|Any CPU') $sln = $sln.Replace('.Deployment|Any CPU.Build.0 = Debug|Any CPU', '.Deployment|Any CPU.Build.0 = Release|Any CPU') $sln = $sln.Replace('.Deployment|Mixed Platforms.ActiveCfg = Debug|Any CPU', '.Deployment|Mixed Platforms.ActiveCfg = Release|Any CPU') $sln = $sln.Replace('.Deployment|Mixed Platforms.Build.0 = Debug|Any CPU', '.Deployment|Mixed Platforms.Build.0 = Release|Any CPU') $sln = $sln.Replace('.Deployment|.NET.ActiveCfg = Debug|Any CPU', '.Deployment|.NET.ActiveCfg = Release|Any CPU') $sln = $sln.Replace('.Debug|.NET.ActiveCfg = Deployment|.NET', '.Debug|.NET.ActiveCfg = Development|.NET')   [System.IO.File]::WriteAllText($path, $sln) The script creates a backup of the solution file first, and then fixes up all the configs to use the correct builds. It's a simple search and replace list, so if there are any patterns that need to be added let me know and I'll update the script. A RegEx replace would be neater, but when it comes to hacking solution files, I prefer the conservative approach of knowing exactly what you're changing.

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