How to enable the garbage collection trace facilities on IBM Java 2 SDK 1.4.2
 Technote (FAQ)
 
Problem
This document describes how to enable the garbage collection trace facilities on Java™ SDK 1.4.2.
 
Solution
From IBM® Java 2 SDK version 1.4.2, 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 1.4.2, the -Xtgc functionality is achieved by using -Dibm.dg.trc.print

For example, you can use the following in 1.4.2:

1.3.1 1.4.2
-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_terse Dumps the contents of the heap before and after a garbage collection.
st_verify Verifies the integrity of the heap before and after a compaction.
st_mark Traces all the objects that are found during the conservative part of marking.
st_compact Traces all the moves that occur during a compaction.
st_compact_verbose Runs only with st_verify; shows all the pinned and dosed objects that are on the heap before a compaction.
st_compact_dump Runs only with st_verify; dumps the contents of the heap before a compaction and after a compaction.
st_dump Runs 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_alloc Traces every heap lock allocation.
st_refs Traces reference handling during garbage collection.
st_backtrace Runs 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_freelist Traces information about the freelist during garbage collection.
st_calloc Traces successful calls to realObjCalloc() and transientRealObjCalloc().
st_parallel Traces the activity of parallel mark and parallel sweep, producing some statistics.
st_trace Traces all the work that is done by the mark phase.
st_concurrent Traces the state of WorkPackets that are in concurrent mark.
st_concurrent_pck Traces frequent operations on WorkPackets, such as getting, or returning.
st_icompact Traces, 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.
 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers Runtimes for Java Technology Java SDK
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Java SDK
Operating system(s): Windows
Software version: 6.0
Software edition:
Reference #: 1172922
IBM Group: Software Group
Modified date: Dec 8, 2006