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36 lines
1.7 KiB
Markdown
36 lines
1.7 KiB
Markdown
# Advanced Stacktrace Features
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## Display JIT compilation task
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Async-profiler samples JIT compiler threads just the same way as Java threads, and hence can show
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CPU percentage spent on JIT compilation. At the same time, Java methods are different:
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some take more resources to compile, other take less. Furthermore, there are cases when
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a bug in C2 compiler causes a JIT thread to stuck in an infinite loop consuming 100% CPU.
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Async-profiler can highlight which particular Java methods take most CPU time to compile.
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The feature can be enabled with the option `-F comptask` (or its agent equivalent `features=comptask`).
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## Display actual implementation in vtable
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In some applications, a significant amount of CPU time is spent on dispatching megamorphic virtual/interface calls.
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async-profiler shows a pseudo-frame on top of v/itable stub with the actual type of object the virtual method is
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called on. This should make clear the proportion of different receivers for the particular call site.
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The feature can be enabled with the option `-F vtable` (or its agent equivalent `features=vtable`).
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## Display instruction addresses
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Sometimes, for low-level performance analysis, it is important to know where exactly
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CPU time is spent inside a method. As an intermediate step to the instruction-level
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profiling, async-profiler provides an option to record PC address of the currently
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running method for each execution sample. In this case, each stack trace will include
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a synthetic frame with the address at the top of every stack trace.
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The feature can be enabled with the option `-F pcaddr` (or its agent equivalent `features=pcaddr`).
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