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8153224: Monitor deflation prolong safepoints

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Add support for AsyncDeflateIdleMonitors (default true); the async deflation work is performed by the ServiceThread.

Co-authored-by: Carsten Varming <varming@gmail.com>
Reviewed-by: dcubed, rehn, rkennke, cvarming, coleenp, acorn, dholmes, eosterlund
This commit is contained in:
Daniel D. Daugherty 2020-06-01 23:37:14 -04:00
parent 30aa1b0689
commit 00f223e22f
23 changed files with 1496 additions and 250 deletions
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75
src/hotspot/share/runtime/objectMonitor.hpp
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@ -136,13 +136,21 @@ class ObjectMonitor {
// Enforced by the assert() in header_addr().
volatile markWord _header; // displaced object header word - mark
void* volatile _object; // backward object pointer - strong root
private:
typedef enum {
Free = 0, // Free must be 0 for monitor to be free after memset(..,0,..).
New,
Old
} AllocationState;
AllocationState _allocation_state;
// Separate _header and _owner on different cache lines since both can
// have busy multi-threaded access. _header and _object are set at
// initial inflation and _object doesn't change until deflation so
// _object is a good choice to share the cache line with _header.
DEFINE_PAD_MINUS_SIZE(0, OM_CACHE_LINE_SIZE,
sizeof(volatile markWord) + sizeof(void* volatile));
// have busy multi-threaded access. _header, _object and _allocation_state
// are set at initial inflation. _object and _allocation_state don't
// change until deflation so _object and _allocation_state are good
// choices to share the cache line with _header.
DEFINE_PAD_MINUS_SIZE(0, OM_CACHE_LINE_SIZE, sizeof(volatile markWord) +
sizeof(void* volatile) + sizeof(AllocationState));
// Used by async deflation as a marker in the _owner field:
#define DEFLATER_MARKER reinterpret_cast<void*>(-1)
void* volatile _owner; // pointer to owning thread OR BasicLock
volatile jlong _previous_owner_tid; // thread id of the previous owner of the monitor
// Separate _owner and _next_om on different cache lines since
@ -164,9 +172,10 @@ class ObjectMonitor {
volatile int _Spinner; // for exit->spinner handoff optimization
volatile int _SpinDuration;
volatile jint _contentions; // Number of active contentions in enter(). It is used by is_busy()
jint _contentions; // Number of active contentions in enter(). It is used by is_busy()
// along with other fields to determine if an ObjectMonitor can be
// deflated. See ObjectSynchronizer::deflate_monitor().
// deflated. It is also used by the async deflation protocol. See
// ObjectSynchronizer::deflate_monitor() and deflate_monitor_using_JT().
protected:
ObjectWaiter* volatile _WaitSet; // LL of threads wait()ing on the monitor
volatile jint _waiters; // number of waiting threads
@ -233,17 +242,34 @@ class ObjectMonitor {
intptr_t is_busy() const {
// TODO-FIXME: assert _owner == null implies _recursions = 0
return _contentions|_waiters|intptr_t(_owner)|intptr_t(_cxq)|intptr_t(_EntryList);
intptr_t ret_code = _waiters | intptr_t(_cxq) | intptr_t(_EntryList);
if (!AsyncDeflateIdleMonitors) {
ret_code |= contentions() | intptr_t(_owner);
} else {
if (contentions() > 0) {
ret_code |= contentions();
}
if (_owner != DEFLATER_MARKER) {
ret_code |= intptr_t(_owner);
}
}
return ret_code;
}
const char* is_busy_to_string(stringStream* ss);
intptr_t is_entered(Thread* current) const;
void* owner() const;
void* owner() const; // Returns NULL if DEFLATER_MARKER is observed.
// Returns true if owner field == DEFLATER_MARKER and false otherwise.
bool owner_is_DEFLATER_MARKER();
// Returns true if 'this' is being async deflated and false otherwise.
bool is_being_async_deflated();
// Clear _owner field; current value must match old_value.
void release_clear_owner(void* old_value);
// Simply set _owner field to new_value; current value must match old_value.
void set_owner_from(void* old_value, void* new_value);
// Simply set _owner field to new_value; current value must match old_value1 or old_value2.
void set_owner_from(void* old_value1, void* old_value2, void* new_value);
// Simply set _owner field to self; current value must match basic_lock_p.
void set_owner_from_BasicLock(void* basic_lock_p, Thread* self);
// Try to set _owner field to new_value if the current value matches
@ -262,6 +288,7 @@ class ObjectMonitor {
jint waiters() const;
jint contentions() const;
void add_to_contentions(jint value);
intx recursions() const { return _recursions; }
// JVM/TI GetObjectMonitorUsage() needs this:
@ -286,7 +313,9 @@ class ObjectMonitor {
// _cxq == 0 _succ == NULL _owner == NULL _waiters == 0
// _contentions == 0 EntryList == NULL
// _recursions == 0 _WaitSet == NULL
DEBUG_ONLY(stringStream ss;)
#ifdef ASSERT
stringStream ss;
#endif
assert((is_busy() | _recursions) == 0, "freeing in-use monitor: %s, "
"recursions=" INTX_FORMAT, is_busy_to_string(&ss), _recursions);
_succ = NULL;
@ -301,13 +330,19 @@ class ObjectMonitor {
void* object() const;
void* object_addr();
void set_object(void* obj);
void set_allocation_state(AllocationState s);
AllocationState allocation_state() const;
bool is_free() const;
bool is_old() const;
bool is_new() const;
// Returns true if the specified thread owns the ObjectMonitor. Otherwise
// returns false and throws IllegalMonitorStateException (IMSE).
bool check_owner(Thread* THREAD);
void clear();
void clear_common();
void enter(TRAPS);
bool enter(TRAPS);
void exit(bool not_suspended, TRAPS);
void wait(jlong millis, bool interruptable, TRAPS);
void notify(TRAPS);
@ -321,7 +356,7 @@ class ObjectMonitor {
// Use the following at your own risk
intx complete_exit(TRAPS);
void reenter(intx recursions, TRAPS);
bool reenter(intx recursions, TRAPS);
private:
void AddWaiter(ObjectWaiter* waiter);
@ -332,10 +367,22 @@ class ObjectMonitor {
void ReenterI(Thread* self, ObjectWaiter* self_node);
void UnlinkAfterAcquire(Thread* self, ObjectWaiter* self_node);
int TryLock(Thread* self);
int NotRunnable(Thread* self, Thread * Owner);
int NotRunnable(Thread* self, Thread* Owner);
int TrySpin(Thread* self);
void ExitEpilog(Thread* self, ObjectWaiter* Wakee);
bool ExitSuspendEquivalent(JavaThread* self);
void install_displaced_markword_in_object(const oop obj);
};
// Macro to use guarantee() for more strict AsyncDeflateIdleMonitors
// checks and assert() otherwise.
#define ADIM_guarantee(p, ...) \
do { \
if (AsyncDeflateIdleMonitors) { \
guarantee(p, __VA_ARGS__); \
} else { \
assert(p, __VA_ARGS__); \
} \
} while (0)
#endif // SHARE_RUNTIME_OBJECTMONITOR_HPP