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