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.
-------------
Commit messages:
- cleanup debug agent removeThread() api
Changes: https://git.openjdk.org/jdk/pull/10828/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10828&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8295810
Stats: 16 lines in 1 file changed: 1 ins; 8 del; 7 mod
Patch: https://git.openjdk.org/jdk/pull/10828.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/10828/head:pull/10828
PR: https://git.openjdk.org/jdk/pull/10828
