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Compare to AGCT, StackWalker::walkVM() would always output fixed pattern of stack frames. When calling the java Reflection method（Method#invoke: .call_stub()L; These frames are the fixed pattern. Can we just unwind these frames but not to fill the frames, like the AGCT stack backtrace results. |
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Replies: 2 comments 6 replies
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With If you are not interested in such level of detail, use other stack walking modes ( |
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Thank you for your prompt reply. |
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@apangin since you have the start and end addresses for the call stub for other reasons, what do you think about adding an option to terminate the unwind when hitting the call stub? In my experience, Java users don’t care about how the VM runs the Java program, and should focus on things they can control, i.e. most frames below the call stub. If this information is useful to specialist users, the option to unwind further should be available. |
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This is what the default stack walking mode does, isn't it? |
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I thought the primary motivation for the VMStructs unwinder was not crashing in AsyncGetCallTrace? If the VMStructs unwinder is safer, it would be nice if it could be configured to skip frames above the call stub that many (most?) users will find irrelevant. |
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Motivation for this change is discussed in #795: reliability was one of the reasons, but not the only one. |
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"Light" mode of VMStructs stack walker has been added in #1073. |
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With
cstack=vm, async-profiler collects full stack trace of a thread, including all intermediate JVM frames. This is intentional. It was exactly the reason whyvmmode appeared - completeness was one of the main requirements from customers (see #795).If you are not interested in such level of detail, use other stack walking modes (
cstack=dwarfmay be a good option). Alternatively, you may post-process recordings to exclude frames you don't need.