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| 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.printFor example, you can use the following in 1.4.1:1.3.1 | 1.4.1 | -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_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. |
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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
(C) Copyright IBM Corporation 2000, 2004. All Rights Reserved.
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