1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/runtime/park.cpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,168 @@
1.4 +/*
1.5 + * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "precompiled.hpp"
1.29 +#include "runtime/thread.hpp"
1.30 +
1.31 +
1.32 +
1.33 +// Lifecycle management for TSM ParkEvents.
1.34 +// ParkEvents are type-stable (TSM).
1.35 +// In our particular implementation they happen to be immortal.
1.36 +//
1.37 +// We manage concurrency on the FreeList with a CAS-based
1.38 +// detach-modify-reattach idiom that avoids the ABA problems
1.39 +// that would otherwise be present in a simple CAS-based
1.40 +// push-pop implementation. (push-one and pop-all)
1.41 +//
1.42 +// Caveat: Allocate() and Release() may be called from threads
1.43 +// other than the thread associated with the Event!
1.44 +// If we need to call Allocate() when running as the thread in
1.45 +// question then look for the PD calls to initialize native TLS.
1.46 +// Native TLS (Win32/Linux/Solaris) can only be initialized or
1.47 +// accessed by the associated thread.
1.48 +// See also pd_initialize().
1.49 +//
1.50 +// Note that we could defer associating a ParkEvent with a thread
1.51 +// until the 1st time the thread calls park(). unpark() calls to
1.52 +// an unprovisioned thread would be ignored. The first park() call
1.53 +// for a thread would allocate and associate a ParkEvent and return
1.54 +// immediately.
1.55 +
1.56 +volatile int ParkEvent::ListLock = 0 ;
1.57 +ParkEvent * volatile ParkEvent::FreeList = NULL ;
1.58 +
1.59 +ParkEvent * ParkEvent::Allocate (Thread * t) {
1.60 + // In rare cases -- JVM_RawMonitor* operations -- we can find t == null.
1.61 + ParkEvent * ev ;
1.62 +
1.63 + // Start by trying to recycle an existing but unassociated
1.64 + // ParkEvent from the global free list.
1.65 + // Using a spin lock since we are part of the mutex impl.
1.66 + // 8028280: using concurrent free list without memory management can leak
1.67 + // pretty badly it turns out.
1.68 + Thread::SpinAcquire(&ListLock, "ParkEventFreeListAllocate");
1.69 + {
1.70 + ev = FreeList;
1.71 + if (ev != NULL) {
1.72 + FreeList = ev->FreeNext;
1.73 + }
1.74 + }
1.75 + Thread::SpinRelease(&ListLock);
1.76 +
1.77 + if (ev != NULL) {
1.78 + guarantee (ev->AssociatedWith == NULL, "invariant") ;
1.79 + } else {
1.80 + // Do this the hard way -- materialize a new ParkEvent.
1.81 + ev = new ParkEvent () ;
1.82 + guarantee ((intptr_t(ev) & 0xFF) == 0, "invariant") ;
1.83 + }
1.84 + ev->reset() ; // courtesy to caller
1.85 + ev->AssociatedWith = t ; // Associate ev with t
1.86 + ev->FreeNext = NULL ;
1.87 + return ev ;
1.88 +}
1.89 +
1.90 +void ParkEvent::Release (ParkEvent * ev) {
1.91 + if (ev == NULL) return ;
1.92 + guarantee (ev->FreeNext == NULL , "invariant") ;
1.93 + ev->AssociatedWith = NULL ;
1.94 + // Note that if we didn't have the TSM/immortal constraint, then
1.95 + // when reattaching we could trim the list.
1.96 + Thread::SpinAcquire(&ListLock, "ParkEventFreeListRelease");
1.97 + {
1.98 + ev->FreeNext = FreeList;
1.99 + FreeList = ev;
1.100 + }
1.101 + Thread::SpinRelease(&ListLock);
1.102 +}
1.103 +
1.104 +// Override operator new and delete so we can ensure that the
1.105 +// least significant byte of ParkEvent addresses is 0.
1.106 +// Beware that excessive address alignment is undesirable
1.107 +// as it can result in D$ index usage imbalance as
1.108 +// well as bank access imbalance on Niagara-like platforms,
1.109 +// although Niagara's hash function should help.
1.110 +
1.111 +void * ParkEvent::operator new (size_t sz) throw() {
1.112 + return (void *) ((intptr_t (AllocateHeap(sz + 256, mtInternal, CALLER_PC)) + 256) & -256) ;
1.113 +}
1.114 +
1.115 +void ParkEvent::operator delete (void * a) {
1.116 + // ParkEvents are type-stable and immortal ...
1.117 + ShouldNotReachHere();
1.118 +}
1.119 +
1.120 +
1.121 +// 6399321 As a temporary measure we copied & modified the ParkEvent::
1.122 +// allocate() and release() code for use by Parkers. The Parker:: forms
1.123 +// will eventually be removed as we consolide and shift over to ParkEvents
1.124 +// for both builtin synchronization and JSR166 operations.
1.125 +
1.126 +volatile int Parker::ListLock = 0 ;
1.127 +Parker * volatile Parker::FreeList = NULL ;
1.128 +
1.129 +Parker * Parker::Allocate (JavaThread * t) {
1.130 + guarantee (t != NULL, "invariant") ;
1.131 + Parker * p ;
1.132 +
1.133 + // Start by trying to recycle an existing but unassociated
1.134 + // Parker from the global free list.
1.135 + // 8028280: using concurrent free list without memory management can leak
1.136 + // pretty badly it turns out.
1.137 + Thread::SpinAcquire(&ListLock, "ParkerFreeListAllocate");
1.138 + {
1.139 + p = FreeList;
1.140 + if (p != NULL) {
1.141 + FreeList = p->FreeNext;
1.142 + }
1.143 + }
1.144 + Thread::SpinRelease(&ListLock);
1.145 +
1.146 + if (p != NULL) {
1.147 + guarantee (p->AssociatedWith == NULL, "invariant") ;
1.148 + } else {
1.149 + // Do this the hard way -- materialize a new Parker..
1.150 + p = new Parker() ;
1.151 + }
1.152 + p->AssociatedWith = t ; // Associate p with t
1.153 + p->FreeNext = NULL ;
1.154 + return p ;
1.155 +}
1.156 +
1.157 +
1.158 +void Parker::Release (Parker * p) {
1.159 + if (p == NULL) return ;
1.160 + guarantee (p->AssociatedWith != NULL, "invariant") ;
1.161 + guarantee (p->FreeNext == NULL , "invariant") ;
1.162 + p->AssociatedWith = NULL ;
1.163 +
1.164 + Thread::SpinAcquire(&ListLock, "ParkerFreeListRelease");
1.165 + {
1.166 + p->FreeNext = FreeList;
1.167 + FreeList = p;
1.168 + }
1.169 + Thread::SpinRelease(&ListLock);
1.170 +}
1.171 +
