Create a Java heap dump for Wowza Streaming Engine

When you open a Support ticket for Wowza Streaming Engine™ media server software, the Support engineers at Wowza Media Systems™ may ask you to provide a Java heap dump file. This article describes how to get a dump of the Java heap on Wowza Streaming Engine.

Install Java JRE or JDK


To use this method, Wowza Streaming Engine must be running the full Java JRE or JDK, which includes the jcmd tool. By default, Wowza Streaming Engine installs with a custom version of the Java JRE. In order to run the jcmd command, you will first need to:

  1. Download and install the full version of the Java JRE or JDK.
  2. Set your installation of Wowza Streaming Engine to point to the full Java JRE or JDK you just installed. See Manually install and troubleshoot Java on Wowza Streaming Engine.

Create a Java heap dump using jcmd


Notes:
  • The commands in this section must be run by the same user that owns the Java process that's running Wowza Streaming Engine.
  • The default location for Java heap dump files created with the jcmd tool is the Wowza Streaming Engine [install-dir]/bin directory. You can provide an absolute path in your commands if you want to save the heap dump in a different location.
  1. Open a command prompt and run the following command to find the process ID of the Java process that's running Wowza Streaming Engine (com.wowza.wms.bootstrap.Bootstrap):
    jcmd


  2. Then, execute the following command:
     
    jcmd [pid] GC.heap_dump [heap-output-path]/heapdump.hprof

    Where [pid] is the process ID of the process running Wowza Streaming Engine and [heap-output-path] is the path to a writable directory that should contain the heap dump.

Create a Java heap dump using the Wowza Streaming Engine REST API


This method can be used with Wowza Streaming Engine 4.5.0.01 and later.

Note:
  • To get started with the Wowza Streaming Engine REST API, see articles in the Overview section.
  • If the server is not responding, these instructions may not work. We recommend using the jcmd method to create the heap dump instead.

To create a heap dump, use the following request:

curl -X PUT --header 'Accept:application/json; charset=utf-8' --header 'Content-type:application/json; charset=utf-8' http://127.0.0.1:8087/v2/servers/{serverName}/actions/heapDump

This writes the heap dump to [install-dir]/WowzaStreamingEngine_HeapDump_${epoch}.hprof. The ${epoch} variable is replaced with the current system epoch in milliseconds.

You can change the location of the heap dump by including the filename query parameter in the request. For example, to write the heap dump to C:\Temp, use the following request:

curl -X PUT --header 'Accept:application/json; charset=utf-8' --header 'Content-type:application/json; charset=utf-8' http://127.0.0.1:8087/v2/servers/{serverName}/actions/heapDump?filename="C:\Temp\WowzaStreamingEngine_HeapDump_${epoch}.hprof"

Create a Java heap dump using JConsole


Use this method for Wowza Streaming Engine 4.4.1 and earlier.

  1. Use JConsole/JMX to connect to the running Wowza Streaming Engine.
     
  2. On the MBeans tab, in the com.sun.management/HotSpotDiagnostics object, select the Operation section.
     
  3. In dumpHeap parameters, enter the following information:
     
    p0: [heap-output-path]
    p1: true - do a garbage collection before dump heap

    For example:

    p0: c:/dump.dmp
    p1: true
  4. Click the dumpHeap button.

Create a Java heap dump using jHat


To use this method, Wowza Streaming Engine must be running the Java JDK, which includes the Java Heap Analysis Tool (jHat) tool.

  1. Open a command prompt and "change directory" to the bin folder of the JDK installation.
     
  2. Use operating system tools such as ps (ps -ef on Linux or the Task Manager on Windows) to find the process ID of the Java process that's running Wowza Streaming Engine.
     
  3. Execute the following command:
     
    jmap -dump:format=b,file=c:\Temp\heapdump.hprof [pid]

    Where [pid] is the process ID of the process running Wowza Streaming Engine.

Create a Java heap dump automatically when an OutOfMemory error is thrown 


You can configure Java to create a heap dump whenever an "OutOfMemory" error occurs.

Open the [install-dir]/conf/Tune.xml file in a text editor, and then uncomment the following line:

For Linux and macOS:

<VMOption>-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=${com.wowza.wms.AppHome}/logs</VMOption>

For Windows:

<VMOption>-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath="${com.wowza.wms.AppHome}/logs"</VMOption>

Save the file and then restart Wowza Streaming Engine.

Note: To force a garbage collection cycle before creating a heap dump, run the command jcmd [pid] GC.run.

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