Reset JNI Addresses if FSD on restore (0.48) #20122
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If debug is specified on restore, ensure that any proactively compiled JNI Methods are reset to their original address. JNI methods are not compiled under FSD, but they are compiled proactively in the checkpoint hook. However, if debug is specified on restore, all proactively compiled methods, except for JNI thunks, get invalidated. Thus, the extra field of the J9Method of a JNI method needs to get reset to whatever the VM initialized them to originally. This is necessary to ensure an environment that is consistent with FSD mode. The invalidation of proactively compiled non-JNI methods (which are non-FSD bodies) ensure that non-FSD code does not execute post-restore. At the checkpoint hook, only FSD bodies are on the stacks of the threads; although the compiler currently does not reuse these FSD bodies, they will continue to execute on restore until an OSR transition, but this is OK because they are already set up for involuntary OSR. The missing piece was the JNI methods, which this commit addresses. Signed-off-by: Irwin D'Souza <[email protected]>
dsouzai
added this to the Release 0.48 (Java 8, 11, 17, 21, 23) October refresh milestone
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@mpirvu this is the 0.48 backport. fyi @TobiAjila |
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I will wait on this until tomorrow, so that the original fix goes through the nightly testing. |
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I verified that the this change is equivalent to the one in the master branch. |
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If debug is specified on restore, ensure that any proactively compiled JNI Methods are reset to their original address.
JNI methods are not compiled under FSD, but they are compiled proactively in the checkpoint hook. However, if debug is specified on restore, all proactively compiled methods, except for JNI thunks, get invalidated. Thus, the extra field of the J9Method of a JNI method needs to get reset to whatever the VM initialized them to originally.
This is necessary to ensure an environment that is consistent with FSD mode. The invalidation of proactively compiled non-JNI methods (which are non-FSD bodies) ensure that non-FSD code does not execute post-restore. At the checkpoint hook, only FSD bodies are on the stacks of the threads; although the compiler currently does not reuse these FSD bodies, they will continue to execute on restore until an OSR transition, but this is OK because they are already set up for involuntary OSR. The missing piece was the JNI methods, which this commit addresses.
cherry-pick of #20108 (with a merge conflict fixed).