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31 Header for -agentlib:hprof (or -Xrunhprof) ASCII Output (JDK 5.0 JVMTI based)
33 WARNING! This file format is under development, and is subject to
34 change without notice.
36 This file contains the following types of records:
39 THREAD END mark the lifetime of Java threads
41 TRACE represents a Java stack trace. Each trace consists
42 of a series of stack frames. Other records refer to
43 TRACEs to identify (1) where object allocations have
44 taken place, (2) the frames in which GC roots were
45 found, and (3) frequently executed methods.
47 HEAP DUMP is a complete snapshot of all live objects in the Java
48 heap. Following distinctions are made:
50 ROOT root set as determined by GC
55 SITES is a sorted list of allocation sites. This identifies
56 the most heavily allocated object types, and the TRACE
57 at which those allocations occurred.
59 CPU SAMPLES is a statistical profile of program execution. The VM
60 periodically samples all running threads, and assigns
61 a quantum to active TRACEs in those threads. Entries
62 in this record are TRACEs ranked by the percentage of
63 total quanta they consumed; top-ranked TRACEs are
64 typically hot spots in the program.
66 CPU TIME is a profile of program execution obtained by measuring
67 the time spent in individual methods (excluding the time
68 spent in callees), as well as by counting the number of
69 times each method is called. Entries in this record are
70 TRACEs ranked by the percentage of total CPU time. The
71 "count" field indicates the number of times each TRACE
74 MONITOR TIME is a profile of monitor contention obtained by measuring
75 the time spent by a thread waiting to enter a monitor.
76 Entries in this record are TRACEs ranked by the percentage
77 of total monitor contention time and a brief description
78 of the monitor. The "count" field indicates the number of
79 times the monitor was contended at that TRACE.
81 MONITOR DUMP is a complete snapshot of all the monitors and threads in
84 HEAP DUMP, SITES, CPU SAMPLES|TIME and MONITOR DUMP|TIME records are generated
85 at program exit. They can also be obtained during program execution by typing
86 Ctrl-\ (on Solaris) or by typing Ctrl-Break (on Win32).