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8321815: Shenandoah: gc state should be synchronized to java threads …
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…only once per safepoint

Reviewed-by: kdnilsen, ysr
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William Kemper authored and Y. Srinivas Ramakrishna committed Dec 19, 2023
1 parent 459957f commit 808a039
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Showing 5 changed files with 40 additions and 9 deletions.
16 changes: 11 additions & 5 deletions src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -504,6 +504,7 @@ ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
_num_regions(0),
_regions(nullptr),
_update_refs_iterator(this),
_gc_state_changed(false),
_gc_no_progress_count(0),
_control_thread(nullptr),
_shenandoah_policy(policy),
Expand Down Expand Up @@ -1741,16 +1742,21 @@ void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
_update_refs_iterator.reset();
}

void ShenandoahHeap::set_gc_state_all_threads(char state) {
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
ShenandoahThreadLocalData::set_gc_state(t, state);
void ShenandoahHeap::set_gc_state_all_threads() {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
if (_gc_state_changed) {
_gc_state_changed = false;
char state = gc_state();
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
ShenandoahThreadLocalData::set_gc_state(t, state);
}
}
}

void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
_gc_state.set_cond(mask, value);
set_gc_state_all_threads(_gc_state.raw_value());
_gc_state_changed = true;
}

void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
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5 changes: 4 additions & 1 deletion src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,7 @@ class ShenandoahHeap : public CollectedHeap, public ShenandoahSpaceInfo {
friend class ShenandoahGCStateResetter;
friend class ShenandoahParallelObjectIterator;
friend class ShenandoahSafepoint;

// Supported GC
friend class ShenandoahConcurrentGC;
friend class ShenandoahDegenGC;
Expand Down Expand Up @@ -283,6 +284,7 @@ class ShenandoahHeap : public CollectedHeap, public ShenandoahSpaceInfo {
};

private:
bool _gc_state_changed;
ShenandoahSharedBitmap _gc_state;
ShenandoahSharedFlag _degenerated_gc_in_progress;
ShenandoahSharedFlag _full_gc_in_progress;
Expand All @@ -291,11 +293,12 @@ class ShenandoahHeap : public CollectedHeap, public ShenandoahSpaceInfo {

size_t _gc_no_progress_count;

void set_gc_state_all_threads(char state);
void set_gc_state_mask(uint mask, bool value);

public:
char gc_state() const;
void set_gc_state_all_threads();
bool has_gc_state_changed() { return _gc_state_changed; }

void set_concurrent_mark_in_progress(bool in_progress);
void set_evacuation_in_progress(bool in_progress);
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18 changes: 18 additions & 0 deletions src/hotspot/share/gc/shenandoah/shenandoahVMOperations.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,12 +35,23 @@
#include "interpreter/oopMapCache.hpp"
#include "memory/universe.hpp"

bool VM_ShenandoahOperation::doit_prologue() {
assert(!ShenandoahHeap::heap()->has_gc_state_changed(), "GC State can only be changed on a safepoint.");
return true;
}

void VM_ShenandoahOperation::doit_epilogue() {
assert(!ShenandoahHeap::heap()->has_gc_state_changed(), "GC State was not synchronized to java threads.");
}

bool VM_ShenandoahReferenceOperation::doit_prologue() {
VM_ShenandoahOperation::doit_prologue();
Heap_lock->lock();
return true;
}

void VM_ShenandoahReferenceOperation::doit_epilogue() {
VM_ShenandoahOperation::doit_epilogue();
OopMapCache::cleanup_old_entries();
if (Universe::has_reference_pending_list()) {
Heap_lock->notify_all();
Expand All @@ -51,34 +62,41 @@ void VM_ShenandoahReferenceOperation::doit_epilogue() {
void VM_ShenandoahInitMark::doit() {
ShenandoahGCPauseMark mark(_gc_id, "Init Mark", SvcGCMarker::CONCURRENT);
_gc->entry_init_mark();
ShenandoahHeap::heap()->set_gc_state_all_threads();
}

void VM_ShenandoahFinalMarkStartEvac::doit() {
ShenandoahGCPauseMark mark(_gc_id, "Final Mark", SvcGCMarker::CONCURRENT);
_gc->entry_final_mark();
ShenandoahHeap::heap()->set_gc_state_all_threads();
}

void VM_ShenandoahFullGC::doit() {
ShenandoahGCPauseMark mark(_gc_id, "Full GC", SvcGCMarker::FULL);
_full_gc->entry_full(_gc_cause);
ShenandoahHeap::heap()->set_gc_state_all_threads();
}

void VM_ShenandoahDegeneratedGC::doit() {
ShenandoahGCPauseMark mark(_gc_id, "Degenerated GC", SvcGCMarker::CONCURRENT);
_gc->entry_degenerated();
ShenandoahHeap::heap()->set_gc_state_all_threads();
}

void VM_ShenandoahInitUpdateRefs::doit() {
ShenandoahGCPauseMark mark(_gc_id, "Init Update Refs", SvcGCMarker::CONCURRENT);
_gc->entry_init_updaterefs();
ShenandoahHeap::heap()->set_gc_state_all_threads();
}

void VM_ShenandoahFinalUpdateRefs::doit() {
ShenandoahGCPauseMark mark(_gc_id, "Final Update Refs", SvcGCMarker::CONCURRENT);
_gc->entry_final_updaterefs();
ShenandoahHeap::heap()->set_gc_state_all_threads();
}

void VM_ShenandoahFinalRoots::doit() {
ShenandoahGCPauseMark mark(_gc_id, "Final Roots", SvcGCMarker::CONCURRENT);
_gc->entry_final_roots();
ShenandoahHeap::heap()->set_gc_state_all_threads();
}
8 changes: 5 additions & 3 deletions src/hotspot/share/gc/shenandoah/shenandoahVMOperations.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,14 +47,16 @@ class VM_ShenandoahOperation : public VM_Operation {
uint _gc_id;
public:
VM_ShenandoahOperation() : _gc_id(GCId::current()) {};
virtual bool skip_thread_oop_barriers() const { return true; }
bool skip_thread_oop_barriers() const override { return true; }
bool doit_prologue() override;
void doit_epilogue() override;
};

class VM_ShenandoahReferenceOperation : public VM_ShenandoahOperation {
public:
VM_ShenandoahReferenceOperation() : VM_ShenandoahOperation() {};
bool doit_prologue();
void doit_epilogue();
bool doit_prologue() override;
void doit_epilogue() override;
};

class VM_ShenandoahInitMark: public VM_ShenandoahOperation {
Expand Down
2 changes: 2 additions & 0 deletions src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -620,6 +620,8 @@ void ShenandoahVerifier::verify_at_safepoint(const char *label,
guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");
guarantee(ShenandoahVerify, "only when enabled, and bitmap is initialized in ShenandoahHeap::initialize");

ShenandoahHeap::heap()->set_gc_state_all_threads();

// Avoid side-effect of changing workers' active thread count, but bypass concurrent/parallel protocol check
ShenandoahPushWorkerScope verify_worker_scope(_heap->workers(), _heap->max_workers(), false /*bypass check*/);

Expand Down

7 comments on commit 808a039

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Review

Issues

@earthling-amzn
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/backport jdk21u-dev

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@openjdk openjdk bot commented on 808a039 Jan 25, 2024

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@earthling-amzn Could not automatically backport 808a0392 to openjdk/jdk21u-dev due to conflicts in the following files:

  • src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
  • src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp

Please fetch the appropriate branch/commit and manually resolve these conflicts by using the following commands in your personal fork of openjdk/jdk21u-dev. Note: these commands are just some suggestions and you can use other equivalent commands you know.

# Fetch the up-to-date version of the target branch
$ git fetch --no-tags https://git.openjdk.org/jdk21u-dev.git master:master

# Check out the target branch and create your own branch to backport
$ git checkout master
$ git checkout -b backport-earthling-amzn-808a0392

# Fetch the commit you want to backport
$ git fetch --no-tags https://git.openjdk.org/jdk.git 808a03927c153581cbece93a4f5a4f8242b61ef5

# Backport the commit
$ git cherry-pick --no-commit 808a03927c153581cbece93a4f5a4f8242b61ef5
# Resolve conflicts now

# Commit the files you have modified
$ git add files/with/resolved/conflicts
$ git commit -m 'Backport 808a03927c153581cbece93a4f5a4f8242b61ef5'

Once you have resolved the conflicts as explained above continue with creating a pull request towards the openjdk/jdk21u-dev with the title Backport 808a03927c153581cbece93a4f5a4f8242b61ef5.

Below you can find a suggestion for the pull request body:

Hi all,

This pull request contains a backport of commit 808a0392 from the openjdk/jdk repository.

The commit being backported was authored by William Kemper on 19 Dec 2023 and was reviewed by Kelvin Nilsen and Y. Srinivas Ramakrishna.

Thanks!

@earthling-amzn
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/backport jdk22u

@openjdk
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@openjdk openjdk bot commented on 808a039 Jan 25, 2024

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@earthling-amzn the backport was successfully created on the branch backport-earthling-amzn-808a0392 in my personal fork of openjdk/jdk22u. To create a pull request with this backport targeting openjdk/jdk22u:master, just click the following link:

➡️ Create pull request

The title of the pull request is automatically filled in correctly and below you find a suggestion for the pull request body:

Hi all,

This pull request contains a backport of commit 808a0392 from the openjdk/jdk repository.

The commit being backported was authored by William Kemper on 19 Dec 2023 and was reviewed by Kelvin Nilsen and Y. Srinivas Ramakrishna.

Thanks!

If you need to update the source branch of the pull then run the following commands in a local clone of your personal fork of openjdk/jdk22u:

$ git fetch https://github.com/openjdk-bots/jdk22u.git backport-earthling-amzn-808a0392:backport-earthling-amzn-808a0392
$ git checkout backport-earthling-amzn-808a0392
# make changes
$ git add paths/to/changed/files
$ git commit --message 'Describe additional changes made'
$ git push https://github.com/openjdk-bots/jdk22u.git backport-earthling-amzn-808a0392

⚠️ @earthling-amzn You are not yet a collaborator in my fork openjdk-bots/jdk22u. An invite will be sent out and you need to accept it before you can proceed.

@earthling-amzn
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@earthling-amzn earthling-amzn commented on 808a039 Jan 25, 2024 •
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/backport jdk21u-dev

Try this again after integrating deletion of unused code.

@openjdk
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@openjdk openjdk bot commented on 808a039 Jan 25, 2024

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@earthling-amzn Could not automatically backport 808a0392 to openjdk/jdk21u-dev due to conflicts in the following files:

  • src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
  • src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp

Please fetch the appropriate branch/commit and manually resolve these conflicts by using the following commands in your personal fork of openjdk/jdk21u-dev. Note: these commands are just some suggestions and you can use other equivalent commands you know.

# Fetch the up-to-date version of the target branch
$ git fetch --no-tags https://git.openjdk.org/jdk21u-dev.git master:master

# Check out the target branch and create your own branch to backport
$ git checkout master
$ git checkout -b backport-earthling-amzn-808a0392

# Fetch the commit you want to backport
$ git fetch --no-tags https://git.openjdk.org/jdk.git 808a03927c153581cbece93a4f5a4f8242b61ef5

# Backport the commit
$ git cherry-pick --no-commit 808a03927c153581cbece93a4f5a4f8242b61ef5
# Resolve conflicts now

# Commit the files you have modified
$ git add files/with/resolved/conflicts
$ git commit -m 'Backport 808a03927c153581cbece93a4f5a4f8242b61ef5'

Once you have resolved the conflicts as explained above continue with creating a pull request towards the openjdk/jdk21u-dev with the title Backport 808a03927c153581cbece93a4f5a4f8242b61ef5.

Below you can find a suggestion for the pull request body:

Hi all,

This pull request contains a backport of commit 808a0392 from the openjdk/jdk repository.

The commit being backported was authored by William Kemper on 19 Dec 2023 and was reviewed by Kelvin Nilsen and Y. Srinivas Ramakrishna.

Thanks!

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