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8315373: Change VirtualThread to unmount after freezing, re-mount before thawing

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Reviewed-by: pchilanomate, mgronlun, sspitsyn
This commit is contained in:
Alan Bateman 2023-09-10 14:57:40 +00:00
parent 68f69417c7
commit 9a83d55887
3 changed files with 32 additions and 37 deletions
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53
src/java.base/share/classes/java/lang/VirtualThread.java
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@ -194,8 +194,11 @@ final class VirtualThread extends BaseVirtualThread {
}
/**
* Runs or continues execution of the continuation on the current thread.
* Runs or continues execution on the current thread. The virtual thread is mounted
* on the current thread before the task runs or continues. It unmounts when the
* task completes or yields.
*/
@ChangesCurrentThread
private void runContinuation() {
// the carrier must be a platform thread
if (Thread.currentThread().isVirtual()) {
@ -217,11 +220,13 @@ final class VirtualThread extends BaseVirtualThread {
// notify JVMTI before mount
notifyJvmtiMount(/*hide*/true);
mount();
try {
cont.run();
} finally {
unmount();
if (cont.isDone()) {
afterTerminate();
afterDone();
} else {
afterYield();
}
@ -285,16 +290,13 @@ final class VirtualThread extends BaseVirtualThread {
}
/**
* Runs a task in the context of this virtual thread. The virtual thread is
* mounted on the current (carrier) thread before the task runs. It unmounts
* from its carrier thread when the task completes.
* Runs a task in the context of this virtual thread.
*/
@ChangesCurrentThread
private void run(Runnable task) {
assert state == RUNNING;
assert Thread.currentThread() == this && state == RUNNING;
// first mount
mount();
// notify JVMTI, may post VirtualThreadStart event
notifyJvmtiStart();
// emit JFR event if enabled
@ -322,12 +324,8 @@ final class VirtualThread extends BaseVirtualThread {
}
} finally {
// last unmount
// notify JVMTI, may post VirtualThreadEnd event
notifyJvmtiEnd();
unmount();
// final state
setState(TERMINATED);
}
}
}
@ -417,21 +415,15 @@ final class VirtualThread extends BaseVirtualThread {
}
/**
* Unmounts this virtual thread, invokes Continuation.yield, and re-mounts the
* thread when continued. When enabled, JVMTI must be notified from this method.
* @return true if the yield was successful
* Invokes Continuation.yield, notifying JVMTI (if enabled) to hide frames until
* the continuation continues.
*/
@Hidden
@ChangesCurrentThread
private boolean yieldContinuation() {
// unmount
notifyJvmtiUnmount(/*hide*/true);
unmount();
try {
return Continuation.yield(VTHREAD_SCOPE);
} finally {
// re-mount
mount();
notifyJvmtiMount(/*hide*/false);
}
}
@ -477,22 +469,22 @@ final class VirtualThread extends BaseVirtualThread {
}
/**
* Invoked after the thread terminates execution. It notifies anyone
* waiting for the thread to terminate.
* Invoked after the continuation completes.
*/
private void afterTerminate() {
afterTerminate(true, true);
private void afterDone() {
afterDone(true, true);
}
/**
* Invoked after the thread terminates (or start failed). This method
* notifies anyone waiting for the thread to terminate.
* Invoked after the continuation completes (or start failed). Sets the thread
* state to TERMINATED and notifies anyone waiting for the thread to terminate.
*
* @param notifyContainer true if its container should be notified
* @param executed true if the thread executed, false if it failed to start
*/
private void afterTerminate(boolean notifyContainer, boolean executed) {
assert (state() == TERMINATED) && (carrierThread == null);
private void afterDone(boolean notifyContainer, boolean executed) {
assert carrierThread == null;
setState(TERMINATED);
if (executed) {
notifyJvmtiUnmount(/*hide*/false);
@ -546,8 +538,7 @@ final class VirtualThread extends BaseVirtualThread {
started = true;
} finally {
if (!started) {
setState(TERMINATED);
afterTerminate(addedToContainer, /*executed*/false);
afterDone(addedToContainer, /*executed*/false);
}
}
}