RFR: 8153133: Thread.dumpStack() can use StackWalker [v3]

[Mandy Chung]

On Mon, 8 Nov 2021 16:05:12 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Can I please get a review of this change which seeks to implement the enhancement noted in https://bugs.openjdk.java.net/browse/JDK-8153133?
>> 
>> The commit in this PR uses the `StackWalker` API to dump the stacktrace of the thread. A few things to note about this change:
>> 
>> - Previously, the dumped stacktrace would be preceded by a line (from the `Exception` instance) which would state `java.lang.Exception: Stack trace` and the rest of the lines would be the stacktrace. The change in this PR does a small (unrelated) enhacement  which now includes the thread name in the message. So something like `MainThread Stack trace` where `MainThread` is the name of the thread whose stacktrace is being dumped. The linked JBS doesn't mention this change as a necessity but I decided to include it in this PR since I've always missed the thread name in that dumped stacktrace and since we are now using the StackWalker API, the mention of `java.lang.Exception: ...` line in the thread dump will no longer make sense (unless we wanted backward compatibility)
>> - The change doesn't use lambda to allow `Thread.dumpStack()` to be called (for debugging purposes) from places where lambda usage might be too early. 
>> - The change also includes a fallback to use the `Exception.printStackTrace()` to allow for calls to `Thread.dumpStack()` when `StackWalker` class itself is being initialized.
>> 
>> The PR also includes a new jtreg test which verifies this change. The test has 3 test actions - one without security manager, one with security manager and one with `java.security.debug=access,stack` to exercise the case where Thread.dumpStack() gets called during StackWalker class initialization.
>> 
>> The linked JBS issue notes that it would be good to use the StackWalker API even in the `Thread.getStackTrace` implementation. This PR however doesn't include that change because I wanted to tackle that separately since I think that would need to run some performance benchmarks to evaluate any performance changes. The current `Thread.dumpStack` method clearly states that it is meant for debugging purposes so I haven't run any kind of performance benchmarks on this change.
>
> Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix jcheck failure - convert tab to space

@jaikiran Thanks for making this change and identifying the recursive initialization issue.   I also concur with Alan that replacing Thread::dumpStack implementation with StackWalker does not buy us much.   It has to fallback to `new Throwable().printStackTrace()` in some cases.   I think we should close this RFE as will not fix.

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PR: https://git.openjdk.java.net/jdk/pull/6292