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List:       openjdk-serviceability-dev
Subject:    Integrated: 8295810: cleanup debug agent removeThread() api
From:       Chris Plummer <cjplummer () openjdk ! org>
Date:       2022-10-25 16:32:37
Message-ID: AmmB4ubTR9EUvjmiEvmd7vu7t67uwItvg0lrpiG4GgI=.fa6cc67f-962e-42d7-93d4-76fc86874c7f () github ! com
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On Sat, 22 Oct 2022 03:05:07 GMT, Chris Plummer <cjplummer@openjdk.org> wrote:

> The implementation of removeThread() is currently:
> 
> 
> static void
> removeThread(JNIEnv *env, ThreadList *list, jthread thread)
> {
> ThreadNode *node;
> 
> node = findThread(list, thread);
> if (node != NULL) {
> removeNode(list, node);
> clearThread(env, node);
> }
> }
> 
> However, currently all callers already have the ThreadNode*, so they end up calling \
> like the following: 
> `            removeThread(env, list, node->thread);`
> 
> So we go from a ThreadNode* to a jthread, only to do a findThread() to get the \
> ThreadNode* again. Also, the list is stored in the ThreadNode. removeThread() can \
> instead be implemented as: 
> 
> static void
> removeThread(JNIEnv *env, ThreadNode *node)
> {
> JDI_ASSERT(node != NULL);
> removeNode(node->list, node);
> clearThread(env, node);
> }
> 
> 
> This is faster, although not by as much as you might think. TLS is used to map a \
> jthread to a ThreadNode*, so the findThread() call is actually already pretty fast. \
> The exception is when dealing with the otherThreads list. These threads have not \
> yet been started, so TLS cannot be used, but it is rare for threads to appear on \
> this list. Still, this is a good cleanup to do, and should be a bit faster. 
> This cleanup was initially implemented as part of the work for \
> [JDK-8295376](https://bugs.openjdk.org/browse/JDK-8295376), but is being split out.

This pull request has now been integrated.

Changeset: 6289600f
Author:    Chris Plummer <cjplummer@openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/6289600fe86bf1f8de160ea64cdba960b2d3e693
                
Stats:     16 lines in 1 file changed: 1 ins; 8 del; 7 mod

8295810: cleanup debug agent removeThread() api

Reviewed-by: kevinw, sspitsyn, amenkov

-------------

PR: https://git.openjdk.org/jdk/pull/10828


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