65 lines
2.2 KiB
Plaintext
65 lines
2.2 KiB
Plaintext
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'hotspot_jni' PROBES DESCRIPTION
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================================
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This directory contains D scripts which demonstrate usage of 'hotspot_jni'
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provider probes.
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In order to call from native code to Java code, due to embedding of the VM
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in an application or execution of native code within a Java application, the
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native code must make a call through the JNI interface. The JNI interface
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provides a number of methods for invoking Java code and examining the state
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of the VM. DTrace probes are provided at the entry point and return point
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for each of these methods. The probes are provided by the hotspot_jni
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provider. The name of the probe is the name of the JNI method, appended with
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"-entry" for entry probes, and "-return" for return probes. The arguments
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available at each entry probe are the arguments that were provided to the
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function (with the exception of the Invoke* methods, which omit the
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arguments that are passed to the Java method). The return probes have the
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return value of the method as an argument (if available).
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You can find more information about HotSpot probes here:
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http://java.sun.com/javase/6/docs/technotes/guides/vm/dtrace.html
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===========
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THE SCRIPTS
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===========
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The following scripts/samples which demonstrate hotspot_jni probes usage are
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available:
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- CriticalSection.d
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Inspect a JNI application for Critical Section violations.
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- CriticalSection_slow.d
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Do the same as CriticalSection.d but provide more debugging info.
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- hotspot_jni_calls_stat.d
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This script collects statistics about how many times particular JNI method
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has been called.
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- hotspot_jni_calls_tree.d
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The script prints tree of JNI method calls.
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See more details in the scripts.
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==========
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HOW TO RUN
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==========
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To run any dscript from hotspot directory you can do either:
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# dscript.d -c "java ..."
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or if you don't have Solaris 10 patch which allows to specify probes that
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don't yet exist ( Hotspot DTrace probes are defined in libjvm.so and as
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result they could be not been yet loaded when you try to attach dscript to
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the Java process) do:
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# ../helpers/dtrace_helper.d -c "java ..." dscript.d
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or if your application is already running you can just simply attach
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the D script like:
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# dscript.d -p JAVA_PID
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