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ICorProfilerCallback4::ReJITCompilationStarted Method

  • Article

Notifies the profiler that the just-in-time (JIT) compiler has started to recompile a function.

Syntax

HRESULT ReJITCompilationStarted(
    [in] FunctionID functionId,  
    [in] ReJITID    rejitId,  
    [in] BOOL       fIsSafeToBlock);

Parameters

functionId
[in] The ID of the function that the JIT compiler has started to recompile.

rejitId
[in] The recompilation ID of the new version of the function.

fIsSafeToBlock
[in] true to indicate that blocking may cause the runtime to wait for the calling thread to return from this callback; false to indicate that blocking will not affect the operation of the runtime. A value of true does not harm the runtime, but can affect the profiling results.

Remarks

It is possible to receive more than one pair of ReJITCompilationStarted and ReJITCompilationFinished method calls for each function because of the way the runtime handles class constructors. For example, the runtime starts to recompile method A, but the class constructor for class B needs to be run. Therefore, the runtime recompiles the constructor for class B and runs it. While the constructor is running, it makes a call to method A, which causes method A to be recompiled again. In this scenario, the first recompilation of method A is halted. However, both attempts to recompile method A are reported with JIT recompilation events.

Profilers must support the sequence of JIT recompilation callbacks in cases where two threads are simultaneously making callbacks. For example, thread A calls ReJITCompilationStarted; however, before thread A calls ReJITCompilationFinished, thread B calls ICorProfilerCallback::ExceptionSearchFunctionEnter with the function ID from the ReJITCompilationStarted callback for thread A. It might appear that the function ID should not yet be valid because a call to ReJITCompilationFinished had not yet been received by the profiler. However, in this case, the function ID is valid.

Requirements

Platforms: See System Requirements.

Header: CorProf.idl, CorProf.h

Library: CorGuids.lib

.NET Framework Versions: Available since 4.5

See also