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8257189: Handle concurrent updates of MH.form better

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Reviewed-by: redestad, psandoz
This commit is contained in:
Vladimir Ivanov 2020-12-02 17:35:41 +00:00
parent 670426646d
commit 692b273ec5
5 changed files with 69 additions and 53 deletions
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25
src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java
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@ -841,21 +841,9 @@ abstract class MethodHandleImpl {
return (asTypeCache = wrapper);
}
// Customize target if counting happens for too long.
private int invocations = CUSTOMIZE_THRESHOLD;
private void maybeCustomizeTarget() {
int c = invocations;
if (c >= 0) {
if (c == 1) {
target.customize();
}
invocations = c - 1;
}
}
boolean countDown() {
int c = count;
maybeCustomizeTarget();
target.maybeCustomize(); // customize if counting happens for too long
if (c <= 1) {
// Try to limit number of updates. MethodHandle.updateForm() doesn't guarantee LF update visibility.
if (isCounting) {
@ -872,12 +860,15 @@ abstract class MethodHandleImpl {
@Hidden
static void maybeStopCounting(Object o1) {
CountingWrapper wrapper = (CountingWrapper) o1;
final CountingWrapper wrapper = (CountingWrapper) o1;
if (wrapper.countDown()) {
// Reached invocation threshold. Replace counting behavior with a non-counting one.
LambdaForm lform = wrapper.nonCountingFormProducer.apply(wrapper.target);
lform.compileToBytecode(); // speed up warmup by avoiding LF interpretation again after transition
wrapper.updateForm(lform);
wrapper.updateForm(new Function<>() {
public LambdaForm apply(LambdaForm oldForm) {
LambdaForm lform = wrapper.nonCountingFormProducer.apply(wrapper.target);
lform.compileToBytecode(); // speed up warmup by avoiding LF interpretation again after transition
return lform;
}});
}
}