IBM User Guide for Java V7 on Windows > Troubleshooting and support > Using diagnostic tools > Tracing Java applications and the JVM > Controlling the trace > Detailed descriptions of trace options

trigger=<clause>[,<clause>][,<clause>]...

This trace option determines when various triggered trace actions occur. Supported actions include turning tracing on and off for all threads, turning tracing on or off for the current thread, or producing various dumps.

This trace option does not control what is traced. It controls only whether the information that has been selected by the other trace options is produced as normal or is blocked.

Each clause of the trigger option can be tpnid{...}, method{...}, or group{...}. You can specify multiple clauses of the same type if required, but you do not need to specify all types. The clause types are as follows:

method{<methodspec>[,<entryAction>[,<exitAction>[,<delayCount>

[,<matchcount>]]]]}

On entering a method that matches <methodspec>, the specified <entryAction> is run. On leaving a method that matches <methodspec>, the specified <exitAction> is run. If you specify a <delayCount>, the actions are performed only after a matching <methodspec> has been entered that many times. If you specify a <matchCount>, <entryAction> and <exitAction> are performed at most that many times.

group{<groupname>,<action>[,<delayCount>[,<matchcount>]]}

On finding any active tracepoint that is defined as being in trace group <groupname>, for example Entry or Exit, the specified action is run. If you specify a <delayCount>, the action is performed only after that many active tracepoints from group <groupname> have been found. If you specify a <matchCount>, <action> is performed at most that many times.

tpnid{<tpnid>|<tpnidRange>,<action>[,<delayCount>[,<matchcount>]]}

On finding the specified active <tpnid> (tracepoint ID) or a <tpnid> that falls inside the specified <tpnidRange>, the specified action is run. If you specify a <delayCount>, the action is performed only after the JVM finds such an active <tpnid> that many times. If you specify a <matchCount>, <action> is performed at most that many times.

Actions

Wherever an action must be specified, you must select from these choices:

abort

Halt the JVM.

coredump

See sysdump.

heapdump

Produce a Heapdump. See Using Heapdump.

javadump

Produce a Javadump. See Using Javadump.

jstacktrace

Examine the Java stack of the current thread and generate auxiliary tracepoints for each stack frame. The auxiliary tracepoints are written to the same destination as the tracepoint or method trace that triggered the action. You can control the number of stack frames examined with the stackdepth=n option. See stackdepth=<n>.

resume

Resume all tracing (except for threads that are suspended by the action of the resumecount property and Trace.suspendThis() calls).

resumethis

Decrement the suspend count for this thread. If the suspend count is zero or less, resume tracing for this thread.

segv

Cause a segmentation violation. (Intended for use in debugging.)

sleep

Delay the current thread for a length of time controlled by the sleeptime option. The default is 30 seconds. See sleeptime=nnn|aaams|bbbs.

snap

Snap all active trace buffers to a file in the current working directory. The file name has the format: Snapnnnn.yyyymmdd.hhmmssth.ppppp.trc, where nnnn is the sequence number of the snap file since JVM startup, yyyymmdd is the date, hhmmssth is the time, and ppppp is the process ID in decimal with leading zeros removed.

suspend

Suspend all tracing (except for special trace points).

suspendthis

Increment the suspend count for this thread. If the suspend-count is greater than zero, prevent all tracing for this thread.

sysdump (or coredump)

Produce a system dump. See Using system dumps and the dump viewer.

Examples

• To start tracing this thread when it enters any method in java/lang/String, and to stop tracing the thread after exiting the method:

  -Xtrace:resumecount=1
  -Xtrace:trigger=method{java/lang/String.*,resumethis,suspendthis}

• To resume all tracing when any thread enters a method in any class that starts with "error":

  -Xtrace:trigger=method{*.error*,resume}

• To produce a core dump when you reach the 1000th and 1001st tracepoint from the "jvmri" trace group.

  Note: Without <matchcount>, you risk filling your disk with coredump files.

  -Xtrace:trigger=group{staticmethods,coredump,1000,2}

  If using the trigger option generates multiple dumps in rapid succession (more than one per second), specify a dump option to guarantee unique dump names. See Using dump agents for more information.

• To trace (all threads) while the application is active; that is, not starting or shut down. (The application name is "HelloWorld"):

  -Xtrace:suspend,trigger=method{HelloWorld.main,resume,suspend}

• To print a Java stack trace to the console when the mycomponent.1 tracepoint is reached:

  -Xtrace:print=mycomponent.1,trigger=tpnid{mycomponent.1,jstacktrace} 

• To write a Java stack trace to the trace output file when the Sample.code() method is called:

  -Xtrace:maximal=mt,output=trc.out,methods={mycompany/mypackage/Sample.code},
  trigger=method{mycompany/mypackage/Sample.code,jstacktrace}

Parent: Detailed descriptions of trace options

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