1.1 --- a/src/share/vm/runtime/biasedLocking.cpp Wed Oct 14 16:43:13 2020 +0800
1.2 +++ b/src/share/vm/runtime/biasedLocking.cpp Wed Oct 14 17:44:48 2020 +0800
1.3 @@ -31,6 +31,8 @@
1.4 #include "runtime/vframe.hpp"
1.5 #include "runtime/vmThread.hpp"
1.6 #include "runtime/vm_operations.hpp"
1.7 +#include "jfr/support/jfrThreadId.hpp"
1.8 +#include "jfr/jfrEvents.hpp"
1.9
1.10 static bool _biased_locking_enabled = false;
1.11 BiasedLockingCounters BiasedLocking::_counters;
1.12 @@ -142,8 +144,9 @@
1.13 return info;
1.14 }
1.15
1.16 -
1.17 -static BiasedLocking::Condition revoke_bias(oop obj, bool allow_rebias, bool is_bulk, JavaThread* requesting_thread) {
1.18 +// After the call, *biased_locker will be set to obj->mark()->biased_locker() if biased_locker != NULL,
1.19 +// AND it is a living thread. Otherwise it will not be updated, (i.e. the caller is responsible for initialization).
1.20 +static BiasedLocking::Condition revoke_bias(oop obj, bool allow_rebias, bool is_bulk, JavaThread* requesting_thread, JavaThread** biased_locker) {
1.21 markOop mark = obj->mark();
1.22 if (!mark->has_bias_pattern()) {
1.23 if (TraceBiasedLocking) {
1.24 @@ -253,6 +256,13 @@
1.25 }
1.26 }
1.27
1.28 +#if INCLUDE_JFR
1.29 + // If requested, return information on which thread held the bias
1.30 + if (biased_locker != NULL) {
1.31 + *biased_locker = biased_thread;
1.32 + }
1.33 +#endif // INCLUDE_JFR
1.34 +
1.35 return BiasedLocking::BIAS_REVOKED;
1.36 }
1.37
1.38 @@ -373,7 +383,7 @@
1.39
1.40 // At this point we're done. All we have to do is potentially
1.41 // adjust the header of the given object to revoke its bias.
1.42 - revoke_bias(o, attempt_rebias_of_object && klass->prototype_header()->has_bias_pattern(), true, requesting_thread);
1.43 + revoke_bias(o, attempt_rebias_of_object && klass->prototype_header()->has_bias_pattern(), true, requesting_thread, NULL);
1.44 } else {
1.45 if (TraceBiasedLocking) {
1.46 ResourceMark rm;
1.47 @@ -395,14 +405,14 @@
1.48 oop owner = mon_info->owner();
1.49 markOop mark = owner->mark();
1.50 if ((owner->klass() == k_o) && mark->has_bias_pattern()) {
1.51 - revoke_bias(owner, false, true, requesting_thread);
1.52 + revoke_bias(owner, false, true, requesting_thread, NULL);
1.53 }
1.54 }
1.55 }
1.56
1.57 // Must force the bias of the passed object to be forcibly revoked
1.58 // as well to ensure guarantees to callers
1.59 - revoke_bias(o, false, true, requesting_thread);
1.60 + revoke_bias(o, false, true, requesting_thread, NULL);
1.61 }
1.62
1.63 if (TraceBiasedLocking) {
1.64 @@ -445,19 +455,22 @@
1.65 GrowableArray<Handle>* _objs;
1.66 JavaThread* _requesting_thread;
1.67 BiasedLocking::Condition _status_code;
1.68 + traceid _biased_locker_id;
1.69
1.70 public:
1.71 VM_RevokeBias(Handle* obj, JavaThread* requesting_thread)
1.72 : _obj(obj)
1.73 , _objs(NULL)
1.74 , _requesting_thread(requesting_thread)
1.75 - , _status_code(BiasedLocking::NOT_BIASED) {}
1.76 + , _status_code(BiasedLocking::NOT_BIASED)
1.77 + , _biased_locker_id(0) {}
1.78
1.79 VM_RevokeBias(GrowableArray<Handle>* objs, JavaThread* requesting_thread)
1.80 : _obj(NULL)
1.81 , _objs(objs)
1.82 , _requesting_thread(requesting_thread)
1.83 - , _status_code(BiasedLocking::NOT_BIASED) {}
1.84 + , _status_code(BiasedLocking::NOT_BIASED)
1.85 + , _biased_locker_id(0) {}
1.86
1.87 virtual VMOp_Type type() const { return VMOp_RevokeBias; }
1.88
1.89 @@ -486,7 +499,15 @@
1.90 if (TraceBiasedLocking) {
1.91 tty->print_cr("Revoking bias with potentially per-thread safepoint:");
1.92 }
1.93 - _status_code = revoke_bias((*_obj)(), false, false, _requesting_thread);
1.94 +
1.95 + JavaThread* biased_locker = NULL;
1.96 + _status_code = revoke_bias((*_obj)(), false, false, _requesting_thread, &biased_locker);
1.97 +#if INCLUDE_JFR
1.98 + if (biased_locker != NULL) {
1.99 + _biased_locker_id = JFR_THREAD_ID(biased_locker);
1.100 + }
1.101 +#endif // INCLUDE_JFR
1.102 +
1.103 clean_up_cached_monitor_info();
1.104 return;
1.105 } else {
1.106 @@ -500,6 +521,10 @@
1.107 BiasedLocking::Condition status_code() const {
1.108 return _status_code;
1.109 }
1.110 +
1.111 + traceid biased_locker() const {
1.112 + return _biased_locker_id;
1.113 + }
1.114 };
1.115
1.116
1.117 @@ -609,23 +634,44 @@
1.118 if (TraceBiasedLocking) {
1.119 tty->print_cr("Revoking bias by walking my own stack:");
1.120 }
1.121 - BiasedLocking::Condition cond = revoke_bias(obj(), false, false, (JavaThread*) THREAD);
1.122 + EventBiasedLockSelfRevocation event;
1.123 + BiasedLocking::Condition cond = revoke_bias(obj(), false, false, (JavaThread*) THREAD, NULL);
1.124 ((JavaThread*) THREAD)->set_cached_monitor_info(NULL);
1.125 assert(cond == BIAS_REVOKED, "why not?");
1.126 + if (event.should_commit()) {
1.127 + event.set_lockClass(k);
1.128 + event.commit();
1.129 + }
1.130 return cond;
1.131 } else {
1.132 + EventBiasedLockRevocation event;
1.133 VM_RevokeBias revoke(&obj, (JavaThread*) THREAD);
1.134 VMThread::execute(&revoke);
1.135 + if (event.should_commit() && (revoke.status_code() != NOT_BIASED)) {
1.136 + event.set_lockClass(k);
1.137 + // Subtract 1 to match the id of events committed inside the safepoint
1.138 + event.set_safepointId(SafepointSynchronize::safepoint_counter() - 1);
1.139 + event.set_previousOwner(revoke.biased_locker());
1.140 + event.commit();
1.141 + }
1.142 return revoke.status_code();
1.143 }
1.144 }
1.145
1.146 assert((heuristics == HR_BULK_REVOKE) ||
1.147 (heuristics == HR_BULK_REBIAS), "?");
1.148 + EventBiasedLockClassRevocation event;
1.149 VM_BulkRevokeBias bulk_revoke(&obj, (JavaThread*) THREAD,
1.150 (heuristics == HR_BULK_REBIAS),
1.151 attempt_rebias);
1.152 VMThread::execute(&bulk_revoke);
1.153 + if (event.should_commit()) {
1.154 + event.set_revokedClass(obj->klass());
1.155 + event.set_disableBiasing((heuristics != HR_BULK_REBIAS));
1.156 + // Subtract 1 to match the id of events committed inside the safepoint
1.157 + event.set_safepointId(SafepointSynchronize::safepoint_counter() - 1);
1.158 + event.commit();
1.159 + }
1.160 return bulk_revoke.status_code();
1.161 }
1.162
1.163 @@ -645,7 +691,7 @@
1.164 oop obj = h_obj();
1.165 HeuristicsResult heuristics = update_heuristics(obj, false);
1.166 if (heuristics == HR_SINGLE_REVOKE) {
1.167 - revoke_bias(obj, false, false, NULL);
1.168 + revoke_bias(obj, false, false, NULL, NULL);
1.169 } else if ((heuristics == HR_BULK_REBIAS) ||
1.170 (heuristics == HR_BULK_REVOKE)) {
1.171 bulk_revoke_or_rebias_at_safepoint(obj, (heuristics == HR_BULK_REBIAS), false, NULL);
1.172 @@ -661,7 +707,7 @@
1.173 oop obj = (objs->at(i))();
1.174 HeuristicsResult heuristics = update_heuristics(obj, false);
1.175 if (heuristics == HR_SINGLE_REVOKE) {
1.176 - revoke_bias(obj, false, false, NULL);
1.177 + revoke_bias(obj, false, false, NULL, NULL);
1.178 } else if ((heuristics == HR_BULK_REBIAS) ||
1.179 (heuristics == HR_BULK_REVOKE)) {
1.180 bulk_revoke_or_rebias_at_safepoint(obj, (heuristics == HR_BULK_REBIAS), false, NULL);
