How to enable the garbage collection trace facilities on IBM Java 2 SDK 1.4.1

Technote (FAQ)
Problem
This document describes how to enable the garbage collection trace facilities on Java™ SDK 1.4.1.
Solution
From IBM® Java 2 SDK version 1.4.1, garbage collection trace options (previously known as tracegc) have been merged with the JVM RAS trace, and the -Xtgc option is no longer used. Therefore, although the information that is available from this trace remains mostly unchanged, usage of the trace has changed.

In 1.4.1, the -Xtgc functionality is achieved by using -Dibm.dg.trc.print

For example, you can use the following in 1.4.1:

1.3.11.4.1
-Xtgc2-Dibm.dg.trc.print=st_verify
-Xtgc34-Dibm.dg.trc.print=st_compact_verbose,st_verify

Here is the list of available traces:

st_terseDumps the contents of the heap before and after a garbage collection.
st_verifyVerifies the integrity of the heap before and after a compaction.
st_markTraces all the objects that are found during the conservative part of marking.
st_compactTraces all the moves that occur during a compaction.
st_compact_verboseRuns only with st_verify; shows all the pinned and dosed objects that are on the heap before a compaction.
st_compact_dumpRuns only with st_verify; dumps the contents of the heap before a compaction and after a compaction.
st_dumpRuns only with st_verify; displays every free chunk that is in the heap, including dark matter (free chunks that are too small to be on the free list). If it runs with the -Xresettable option, the transient-heap free chunks are also displayed.
st_allocTraces every heap lock allocation.
st_refsTraces reference handling during garbage collection.
st_backtraceRuns only with st_terse; adds one line to the beginning of the st_terse trace. This shows the name of the thread that is running garbage collection, followed by the address of the sys_thread_t structure.
st_freelistTraces information about the freelist during garbage collection.
st_callocTraces successful calls to realObjCalloc() and transientRealObjCalloc().
st_parallelTraces the activity of parallel mark and parallel sweep, producing some statistics.
st_traceTraces all the work that is done by the mark phase.
st_concurrentTraces the state of WorkPackets that are in concurrent mark.
st_concurrent_pckTraces frequent operations on WorkPackets, such as getting, or returning.
st_icompactTraces, by an incremental compaction, all the work that has been done.
st_concurrent_shadow_heap To use this trace, you must also be running the debug build.











    Document Information

    Product categories: Software, Application Servers, Distributed Application & Web Servers, WebSphere Application Server, Java SDK
    Operating system(s): AIX, Linux, Windows
    Software version: 3.5, 4.0, 5.0, 5.1, 6.0
    Reference #: 1172922
    IBM Group: Software Group
    Modified date: 2004-06-25