42 lines
1.7 KiB
HTML
42 lines
1.7 KiB
HTML
<html>
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<head>
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<title>
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Replay
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</title>
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</head>
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<body>
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<h1>Compiler replay</h1>
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<p>
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The compiler replay is a function to repeat the compiling process from a crashed java process in compiled method<br>
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This function only exists in debug version of VM
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</p>
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<h2>Usage</h2>
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<pre>
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First, use SA to attach to the core file, if succeeded, do
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hsdb> dumpreplaydata <address> | -a | <thread_id> [> replay.txt]
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create file replay.txt, address is address of Method, or nmethod(CodeBlob)
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hsdb> buildreplayjars [all | boot | app]
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create files:
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all:
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app.jar, boot.jar
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boot:
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boot.jar
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app:
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app.jar
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exit SA now.
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Second, use the obtained replay text file, replay.txt and jar files, app.jar and boot.jar, using debug version of java
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java -Xbootclasspath/p:boot.jar -cp app.jar -XX:ReplayDataFile=<datafile> -XX:+ReplayCompiles ....
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This will replay the compiling process.
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With ReplayCompiles, the replay will recompile all the methods in app.jar, and in boot.jar to emulate the process in java app.
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notes:
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1) Most time, we don't need the boot.jar which is the classes loaded from JDK. It will be only modified when an agent(JVMDI) is running and modifies the classes.
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2) If encounter error as "<flag>" not found, that means the SA is using a VMStructs which is different from the one with corefile. In this case, SA has a utility tool vmstructsdump which is located at agent/src/os/<os>/proc/<os_platform>
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Use this tool to dump VM type library:
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vmstructsdump libjvm.so > <type_name>.db
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set env SA_TYPEDB=<type_name>.db (refer different shell for set envs)
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