Creating heap dumps for a tc Server instance in Pivotal tc Server

Products

• VMware Tanzu tc Server

Issue/Introduction

Symptoms:
Thread dump and heap dumps are necessary for troubleshooting issues in a Pivotal tc Server instance. This KB walks through the options for obtaining these for your apps running on tc Server.

Environment

Resolution

Thread Dumps

There are a couple options for obtaining a thread dump.

1. Send a `kill -3` to the process id of tc Server. Ex: `kill -3 1234`, where 1234 is the process id of tc Server. This will output the thread dump to `logs/catalina.out`. This only works on Linux/Unix system.
2. Use the `jcmd` or `jstack` tools. Ex: `jstack 1234` or `jcmd 1234 Thread.print`.
3. Use jvisualvm. This is a GUI tool, which can take thread dumps. Locate the local process running in jvisualvm, right click on it and select Thread Dump.

Heap Dumps

There are a number of ways to obtain heap dumps as well.

1. You can implement automatic heap dump generation by adding two parameters to CATALINA_OPTS. This will make the JVM log a heap dump when there is an OutOfMemoryError.
   On Linux you would edit setenv.sh at $CATALINA_HOME/bin:

           export CATALINA_OPTS="$CATALINA_OPTS -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/path/to/heapdumps"

   On Windows, edit setenv.bat:

           set CATALINA_OPTS=%CATALINA_OPTS% -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath="C:\path\to\heapdumps"
   
   These options can also be configured in wrapper.conf as described in this article.

2. You can use `jmap`.  Ex: `jmap -dump:file=heapdump.hprof,format=b <pid>`. This requires the process id of the tc Server instance.
3. You can use `jcmd`. This is exactly the same as `jmap`.  Ex: `jcmd GC.heap_dump filename=heapdump.hprof`.
4. You can use jvisualvm. This is a GUI tool, which can take thread dumps. Locate the local process running in jvisualvm, right click on it and select Thread Dump.
5. You can use Eclipse Memory Analyzer. This is an open source tool for taking and analyzing heap dumps.