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Header for -agentlib:hprof (or -Xrunhprof) ASCII Output (JDK 5.0 JVMTI based) |
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@(#)jvm.hprof.txt 1.5 06/01/28 |
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|
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Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved. |
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|
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WARNING! This file format is under development, and is subject to |
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change without notice. |
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|
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This file contains the following types of records: |
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|
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THREAD START |
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THREAD END mark the lifetime of Java threads |
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|
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TRACE represents a Java stack trace. Each trace consists |
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of a series of stack frames. Other records refer to |
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TRACEs to identify (1) where object allocations have |
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taken place, (2) the frames in which GC roots were |
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found, and (3) frequently executed methods. |
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|
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HEAP DUMP is a complete snapshot of all live objects in the Java |
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heap. Following distinctions are made: |
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|
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ROOT root set as determined by GC |
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CLS classes |
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OBJ instances |
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ARR arrays |
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|
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SITES is a sorted list of allocation sites. This identifies |
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the most heavily allocated object types, and the TRACE |
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at which those allocations occurred. |
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|
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CPU SAMPLES is a statistical profile of program execution. The VM |
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periodically samples all running threads, and assigns |
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a quantum to active TRACEs in those threads. Entries |
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in this record are TRACEs ranked by the percentage of |
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total quanta they consumed; top-ranked TRACEs are |
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typically hot spots in the program. |
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|
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CPU TIME is a profile of program execution obtained by measuring |
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the time spent in individual methods (excluding the time |
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spent in callees), as well as by counting the number of |
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times each method is called. Entries in this record are |
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TRACEs ranked by the percentage of total CPU time. The |
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"count" field indicates the number of times each TRACE |
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is invoked. |
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|
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MONITOR TIME is a profile of monitor contention obtained by measuring |
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the time spent by a thread waiting to enter a monitor. |
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Entries in this record are TRACEs ranked by the percentage |
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of total monitor contention time and a brief description |
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of the monitor. The "count" field indicates the number of |
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times the monitor was contended at that TRACE. |
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|
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MONITOR DUMP is a complete snapshot of all the monitors and threads in |
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the System. |
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|
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HEAP DUMP, SITES, CPU SAMPLES|TIME and MONITOR DUMP|TIME records are generated |
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at program exit. They can also be obtained during program execution by typing |
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Ctrl-\ (on Solaris) or by typing Ctrl-Break (on Win32). |
