Mercurial > hg > truffle
annotate src/share/vm/runtime/sweeper.cpp @ 2428:5134fa1cfe63
7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC
Summary: When verifying clean card ranges, use memory-range-bounded iteration over oops of objects overlapping that range, thus avoiding the otherwise quadratic worst-case cost of scanning large object arrays.
Reviewed-by: jmasa, jwilhelm, tonyp
author | ysr |
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date | Thu, 24 Mar 2011 15:47:01 -0700 |
parents | 1c0cf339481b |
children | 1d1603768966 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "code/codeCache.hpp" | |
27 #include "code/nmethod.hpp" | |
28 #include "compiler/compileBroker.hpp" | |
29 #include "memory/resourceArea.hpp" | |
30 #include "oops/methodOop.hpp" | |
31 #include "runtime/atomic.hpp" | |
32 #include "runtime/compilationPolicy.hpp" | |
33 #include "runtime/mutexLocker.hpp" | |
34 #include "runtime/os.hpp" | |
35 #include "runtime/sweeper.hpp" | |
36 #include "runtime/vm_operations.hpp" | |
37 #include "utilities/events.hpp" | |
38 #include "utilities/xmlstream.hpp" | |
0 | 39 |
40 long NMethodSweeper::_traversals = 0; // No. of stack traversals performed | |
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41 nmethod* NMethodSweeper::_current = NULL; // Current nmethod |
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42 int NMethodSweeper::_seen = 0 ; // No. of nmethods we have currently processed in current pass of CodeCache |
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43 |
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44 volatile int NMethodSweeper::_invocations = 0; // No. of invocations left until we are completed with this pass |
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45 volatile int NMethodSweeper::_sweep_started = 0; // Whether a sweep is in progress. |
0 | 46 |
47 jint NMethodSweeper::_locked_seen = 0; | |
48 jint NMethodSweeper::_not_entrant_seen_on_stack = 0; | |
49 bool NMethodSweeper::_rescan = false; | |
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50 bool NMethodSweeper::_do_sweep = false; |
1202 | 51 bool NMethodSweeper::_was_full = false; |
52 jint NMethodSweeper::_advise_to_sweep = 0; | |
53 jlong NMethodSweeper::_last_was_full = 0; | |
54 uint NMethodSweeper::_highest_marked = 0; | |
55 long NMethodSweeper::_was_full_traversal = 0; | |
0 | 56 |
989 | 57 class MarkActivationClosure: public CodeBlobClosure { |
58 public: | |
59 virtual void do_code_blob(CodeBlob* cb) { | |
60 // If we see an activation belonging to a non_entrant nmethod, we mark it. | |
61 if (cb->is_nmethod() && ((nmethod*)cb)->is_not_entrant()) { | |
62 ((nmethod*)cb)->mark_as_seen_on_stack(); | |
63 } | |
64 } | |
65 }; | |
66 static MarkActivationClosure mark_activation_closure; | |
67 | |
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68 void NMethodSweeper::scan_stacks() { |
0 | 69 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); |
70 if (!MethodFlushing) return; | |
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71 _do_sweep = true; |
0 | 72 |
73 // No need to synchronize access, since this is always executed at a | |
74 // safepoint. If we aren't in the middle of scan and a rescan | |
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75 // hasn't been requested then just return. If UseCodeCacheFlushing is on and |
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76 // code cache flushing is in progress, don't skip sweeping to help make progress |
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77 // clearing space in the code cache. |
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78 if ((_current == NULL && !_rescan) && !(UseCodeCacheFlushing && !CompileBroker::should_compile_new_jobs())) { |
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79 _do_sweep = false; |
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80 return; |
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81 } |
0 | 82 |
83 // Make sure CompiledIC_lock in unlocked, since we might update some | |
84 // inline caches. If it is, we just bail-out and try later. | |
85 if (CompiledIC_lock->is_locked() || Patching_lock->is_locked()) return; | |
86 | |
87 // Check for restart | |
88 assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid"); | |
89 if (_current == NULL) { | |
90 _seen = 0; | |
91 _invocations = NmethodSweepFraction; | |
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92 _current = CodeCache::first_nmethod(); |
0 | 93 _traversals += 1; |
94 if (PrintMethodFlushing) { | |
95 tty->print_cr("### Sweep: stack traversal %d", _traversals); | |
96 } | |
989 | 97 Threads::nmethods_do(&mark_activation_closure); |
0 | 98 |
99 // reset the flags since we started a scan from the beginning. | |
100 _rescan = false; | |
101 _locked_seen = 0; | |
102 _not_entrant_seen_on_stack = 0; | |
103 } | |
104 | |
1202 | 105 if (UseCodeCacheFlushing) { |
106 if (!CodeCache::needs_flushing()) { | |
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107 // scan_stacks() runs during a safepoint, no race with setters |
1202 | 108 _advise_to_sweep = 0; |
109 } | |
110 | |
111 if (was_full()) { | |
112 // There was some progress so attempt to restart the compiler | |
113 jlong now = os::javaTimeMillis(); | |
114 jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; | |
115 jlong curr_interval = now - _last_was_full; | |
116 if ((!CodeCache::needs_flushing()) && (curr_interval > max_interval)) { | |
117 CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); | |
118 set_was_full(false); | |
119 | |
120 // Update the _last_was_full time so we can tell how fast the | |
121 // code cache is filling up | |
122 _last_was_full = os::javaTimeMillis(); | |
123 | |
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124 log_sweep("restart_compiler"); |
1202 | 125 } |
126 } | |
127 } | |
0 | 128 } |
129 | |
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130 void NMethodSweeper::possibly_sweep() { |
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131 assert(JavaThread::current()->thread_state() == _thread_in_vm, "must run in vm mode"); |
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132 if ((!MethodFlushing) || (!_do_sweep)) return; |
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133 |
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134 if (_invocations > 0) { |
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135 // Only one thread at a time will sweep |
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136 jint old = Atomic::cmpxchg( 1, &_sweep_started, 0 ); |
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137 if (old != 0) { |
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138 return; |
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139 } |
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140 if (_invocations > 0) { |
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141 sweep_code_cache(); |
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142 _invocations--; |
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143 } |
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144 _sweep_started = 0; |
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145 } |
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146 } |
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147 |
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148 void NMethodSweeper::sweep_code_cache() { |
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149 #ifdef ASSERT |
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150 jlong sweep_start; |
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151 if (PrintMethodFlushing) { |
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152 sweep_start = os::javaTimeMillis(); |
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153 } |
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154 #endif |
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155 if (PrintMethodFlushing && Verbose) { |
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156 tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_nmethods(), _invocations); |
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157 } |
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158 |
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159 // We want to visit all nmethods after NmethodSweepFraction |
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160 // invocations so divide the remaining number of nmethods by the |
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161 // remaining number of invocations. This is only an estimate since |
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162 // the number of nmethods changes during the sweep so the final |
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163 // stage must iterate until it there are no more nmethods. |
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164 int todo = (CodeCache::nof_nmethods() - _seen) / _invocations; |
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165 |
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166 assert(!SafepointSynchronize::is_at_safepoint(), "should not be in safepoint when we get here"); |
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167 assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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168 |
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169 { |
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170 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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171 |
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172 // The last invocation iterates until there are no more nmethods |
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173 for (int i = 0; (i < todo || _invocations == 1) && _current != NULL; i++) { |
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174 |
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175 // Since we will give up the CodeCache_lock, always skip ahead |
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176 // to the next nmethod. Other blobs can be deleted by other |
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177 // threads but nmethods are only reclaimed by the sweeper. |
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178 nmethod* next = CodeCache::next_nmethod(_current); |
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179 |
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180 // Now ready to process nmethod and give up CodeCache_lock |
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181 { |
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182 MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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183 process_nmethod(_current); |
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184 } |
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185 _seen++; |
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186 _current = next; |
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187 } |
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188 } |
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189 |
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190 assert(_invocations > 1 || _current == NULL, "must have scanned the whole cache"); |
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191 |
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192 if (_current == NULL && !_rescan && (_locked_seen || _not_entrant_seen_on_stack)) { |
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193 // we've completed a scan without making progress but there were |
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194 // nmethods we were unable to process either because they were |
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195 // locked or were still on stack. We don't have to aggresively |
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196 // clean them up so just stop scanning. We could scan once more |
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197 // but that complicates the control logic and it's unlikely to |
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198 // matter much. |
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199 if (PrintMethodFlushing) { |
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200 tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep"); |
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201 } |
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202 } |
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203 |
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204 #ifdef ASSERT |
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205 if(PrintMethodFlushing) { |
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206 jlong sweep_end = os::javaTimeMillis(); |
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207 tty->print_cr("### sweeper: sweep time(%d): " INT64_FORMAT, _invocations, sweep_end - sweep_start); |
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208 } |
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209 #endif |
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210 |
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211 if (_invocations == 1) { |
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212 log_sweep("finished"); |
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213 } |
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214 } |
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215 |
0 | 216 |
217 void NMethodSweeper::process_nmethod(nmethod *nm) { | |
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218 assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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219 |
0 | 220 // Skip methods that are currently referenced by the VM |
221 if (nm->is_locked_by_vm()) { | |
222 // But still remember to clean-up inline caches for alive nmethods | |
223 if (nm->is_alive()) { | |
224 // Clean-up all inline caches that points to zombie/non-reentrant methods | |
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225 MutexLocker cl(CompiledIC_lock); |
0 | 226 nm->cleanup_inline_caches(); |
227 } else { | |
228 _locked_seen++; | |
229 } | |
230 return; | |
231 } | |
232 | |
233 if (nm->is_zombie()) { | |
234 // If it is first time, we see nmethod then we mark it. Otherwise, | |
235 // we reclame it. When we have seen a zombie method twice, we know that | |
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236 // there are no inline caches that refer to it. |
0 | 237 if (nm->is_marked_for_reclamation()) { |
238 assert(!nm->is_locked_by_vm(), "must not flush locked nmethods"); | |
941 | 239 if (PrintMethodFlushing && Verbose) { |
1202 | 240 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (marked for reclamation) being flushed", nm->compile_id(), nm); |
941 | 241 } |
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242 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
0 | 243 nm->flush(); |
244 } else { | |
941 | 245 if (PrintMethodFlushing && Verbose) { |
1202 | 246 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm); |
941 | 247 } |
0 | 248 nm->mark_for_reclamation(); |
249 _rescan = true; | |
250 } | |
251 } else if (nm->is_not_entrant()) { | |
252 // If there is no current activations of this method on the | |
253 // stack we can safely convert it to a zombie method | |
254 if (nm->can_not_entrant_be_converted()) { | |
941 | 255 if (PrintMethodFlushing && Verbose) { |
1202 | 256 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm); |
941 | 257 } |
0 | 258 nm->make_zombie(); |
259 _rescan = true; | |
260 } else { | |
261 // Still alive, clean up its inline caches | |
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262 MutexLocker cl(CompiledIC_lock); |
0 | 263 nm->cleanup_inline_caches(); |
264 // we coudn't transition this nmethod so don't immediately | |
265 // request a rescan. If this method stays on the stack for a | |
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266 // long time we don't want to keep rescanning the code cache. |
0 | 267 _not_entrant_seen_on_stack++; |
268 } | |
269 } else if (nm->is_unloaded()) { | |
270 // Unloaded code, just make it a zombie | |
941 | 271 if (PrintMethodFlushing && Verbose) |
1202 | 272 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (unloaded) being made zombie", nm->compile_id(), nm); |
941 | 273 if (nm->is_osr_method()) { |
0 | 274 // No inline caches will ever point to osr methods, so we can just remove it |
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275 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
0 | 276 nm->flush(); |
277 } else { | |
278 nm->make_zombie(); | |
279 _rescan = true; | |
280 } | |
281 } else { | |
282 assert(nm->is_alive(), "should be alive"); | |
1202 | 283 |
284 if (UseCodeCacheFlushing) { | |
285 if ((nm->method()->code() != nm) && !(nm->is_locked_by_vm()) && !(nm->is_osr_method()) && | |
286 (_traversals > _was_full_traversal+2) && (((uint)nm->compile_id()) < _highest_marked) && | |
287 CodeCache::needs_flushing()) { | |
288 // This method has not been called since the forced cleanup happened | |
289 nm->make_not_entrant(); | |
290 } | |
291 } | |
292 | |
0 | 293 // Clean-up all inline caches that points to zombie/non-reentrant methods |
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294 MutexLocker cl(CompiledIC_lock); |
0 | 295 nm->cleanup_inline_caches(); |
296 } | |
297 } | |
1202 | 298 |
299 // Code cache unloading: when compilers notice the code cache is getting full, | |
300 // they will call a vm op that comes here. This code attempts to speculatively | |
301 // unload the oldest half of the nmethods (based on the compile job id) by | |
302 // saving the old code in a list in the CodeCache. Then | |
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303 // execution resumes. If a method so marked is not called by the second sweeper |
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304 // stack traversal after the current one, the nmethod will be marked non-entrant and |
1202 | 305 // got rid of by normal sweeping. If the method is called, the methodOop's |
306 // _code field is restored and the methodOop/nmethod | |
307 // go back to their normal state. | |
308 void NMethodSweeper::handle_full_code_cache(bool is_full) { | |
309 // Only the first one to notice can advise us to start early cleaning | |
310 if (!is_full){ | |
311 jint old = Atomic::cmpxchg( 1, &_advise_to_sweep, 0 ); | |
312 if (old != 0) { | |
313 return; | |
314 } | |
315 } | |
316 | |
317 if (is_full) { | |
318 // Since code cache is full, immediately stop new compiles | |
319 bool did_set = CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation); | |
320 if (!did_set) { | |
321 // only the first to notice can start the cleaning, | |
322 // others will go back and block | |
323 return; | |
324 } | |
325 set_was_full(true); | |
326 | |
327 // If we run out within MinCodeCacheFlushingInterval of the last unload time, give up | |
328 jlong now = os::javaTimeMillis(); | |
329 jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; | |
330 jlong curr_interval = now - _last_was_full; | |
331 if (curr_interval < max_interval) { | |
332 _rescan = true; | |
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333 log_sweep("disable_compiler", "flushing_interval='" UINT64_FORMAT "'", |
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334 curr_interval/1000); |
1202 | 335 return; |
336 } | |
337 } | |
338 | |
339 VM_HandleFullCodeCache op(is_full); | |
340 VMThread::execute(&op); | |
341 | |
342 // rescan again as soon as possible | |
343 _rescan = true; | |
344 } | |
345 | |
346 void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) { | |
347 // If there was a race in detecting full code cache, only run | |
348 // one vm op for it or keep the compiler shut off | |
349 | |
350 debug_only(jlong start = os::javaTimeMillis();) | |
351 | |
352 if ((!was_full()) && (is_full)) { | |
353 if (!CodeCache::needs_flushing()) { | |
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354 log_sweep("restart_compiler"); |
1202 | 355 CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); |
356 return; | |
357 } | |
358 } | |
359 | |
360 // Traverse the code cache trying to dump the oldest nmethods | |
361 uint curr_max_comp_id = CompileBroker::get_compilation_id(); | |
362 uint flush_target = ((curr_max_comp_id - _highest_marked) >> 1) + _highest_marked; | |
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363 log_sweep("start_cleaning"); |
1202 | 364 |
365 nmethod* nm = CodeCache::alive_nmethod(CodeCache::first()); | |
366 jint disconnected = 0; | |
367 jint made_not_entrant = 0; | |
368 while ((nm != NULL)){ | |
369 uint curr_comp_id = nm->compile_id(); | |
370 | |
371 // OSR methods cannot be flushed like this. Also, don't flush native methods | |
372 // since they are part of the JDK in most cases | |
373 if (nm->is_in_use() && (!nm->is_osr_method()) && (!nm->is_locked_by_vm()) && | |
374 (!nm->is_native_method()) && ((curr_comp_id < flush_target))) { | |
375 | |
376 if ((nm->method()->code() == nm)) { | |
377 // This method has not been previously considered for | |
378 // unloading or it was restored already | |
379 CodeCache::speculatively_disconnect(nm); | |
380 disconnected++; | |
381 } else if (nm->is_speculatively_disconnected()) { | |
382 // This method was previously considered for preemptive unloading and was not called since then | |
1783 | 383 CompilationPolicy::policy()->delay_compilation(nm->method()); |
1202 | 384 nm->make_not_entrant(); |
385 made_not_entrant++; | |
386 } | |
387 | |
388 if (curr_comp_id > _highest_marked) { | |
389 _highest_marked = curr_comp_id; | |
390 } | |
391 } | |
392 nm = CodeCache::alive_nmethod(CodeCache::next(nm)); | |
393 } | |
394 | |
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395 log_sweep("stop_cleaning", |
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396 "disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "'", |
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397 disconnected, made_not_entrant); |
1202 | 398 |
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399 // Shut off compiler. Sweeper will start over with a new stack scan and |
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400 // traversal cycle and turn it back on if it clears enough space. |
1202 | 401 if (was_full()) { |
402 _last_was_full = os::javaTimeMillis(); | |
403 CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation); | |
404 } | |
405 | |
406 // After two more traversals the sweeper will get rid of unrestored nmethods | |
407 _was_full_traversal = _traversals; | |
408 #ifdef ASSERT | |
409 jlong end = os::javaTimeMillis(); | |
410 if(PrintMethodFlushing && Verbose) { | |
411 tty->print_cr("### sweeper: unload time: " INT64_FORMAT, end-start); | |
412 } | |
413 #endif | |
414 } | |
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415 |
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416 |
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417 // Print out some state information about the current sweep and the |
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418 // state of the code cache if it's requested. |
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419 void NMethodSweeper::log_sweep(const char* msg, const char* format, ...) { |
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420 if (PrintMethodFlushing) { |
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421 ttyLocker ttyl; |
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422 tty->print("### sweeper: %s ", msg); |
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423 if (format != NULL) { |
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424 va_list ap; |
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425 va_start(ap, format); |
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426 tty->vprint(format, ap); |
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427 va_end(ap); |
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428 } |
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429 CodeCache::log_state(tty); tty->cr(); |
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430 } |
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431 |
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432 if (LogCompilation && (xtty != NULL)) { |
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433 ttyLocker ttyl; |
1646 | 434 xtty->begin_elem("sweeper state='%s' traversals='" INTX_FORMAT "' ", msg, (intx)traversal_count()); |
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435 if (format != NULL) { |
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436 va_list ap; |
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437 va_start(ap, format); |
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438 xtty->vprint(format, ap); |
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439 va_end(ap); |
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440 } |
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441 CodeCache::log_state(xtty); |
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442 xtty->stamp(); |
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443 xtty->end_elem(); |
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444 } |
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445 } |