1 /*
2 * Copyright (c) 2017, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "code/codeCache.hpp"
26 #include "code/icBuffer.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
29 #include "gc/shenandoah/shenandoahEvacOOMHandler.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
32 #include "gc/shenandoah/shenandoahUtils.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "memory/universe.hpp"
35 #include "runtime/atomic.hpp"
36
37 ShenandoahParallelCodeCacheIterator::ShenandoahParallelCodeCacheIterator(const GrowableArray<CodeHeap*>* heaps) {
38 _length = heaps->length();
39 _iters = NEW_C_HEAP_ARRAY(ShenandoahParallelCodeHeapIterator, _length, mtGC);
40 for (int h = 0; h < _length; h++) {
41 _iters[h] = ShenandoahParallelCodeHeapIterator(heaps->at(h));
42 }
43 }
44
45 ShenandoahParallelCodeCacheIterator::~ShenandoahParallelCodeCacheIterator() {
46 FREE_C_HEAP_ARRAY(ParallelCodeHeapIterator, _iters);
47 }
48
49 void ShenandoahParallelCodeCacheIterator::parallel_blobs_do(CodeBlobClosure* f) {
50 for (int c = 0; c < _length; c++) {
51 _iters[c].parallel_blobs_do(f);
52 }
53 }
54
55 ShenandoahParallelCodeHeapIterator::ShenandoahParallelCodeHeapIterator(CodeHeap* heap) :
56 _heap(heap), _claimed_idx(0), _finished(false) {
57 }
58
59 void ShenandoahParallelCodeHeapIterator::parallel_blobs_do(CodeBlobClosure* f) {
60 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
61
62 /*
63 * Parallel code heap walk.
64 *
65 * This code makes all threads scan all code heaps, but only one thread would execute the
66 * closure on given blob. This is achieved by recording the "claimed" blocks: if a thread
67 * had claimed the block, it can process all blobs in it. Others have to fast-forward to
68 * next attempt without processing.
69 *
70 * Late threads would return immediately if iterator is finished.
71 */
72
73 if (_finished) {
74 return;
75 }
76
77 int stride = 256; // educated guess
78 int stride_mask = stride - 1;
79 assert (is_power_of_2(stride), "sanity");
80
81 int count = 0;
82 bool process_block = true;
83
84 for (CodeBlob *cb = CodeCache::first_blob(_heap); cb != NULL; cb = CodeCache::next_blob(_heap, cb)) {
85 int current = count++;
86 if ((current & stride_mask) == 0) {
87 process_block = (current >= _claimed_idx) &&
88 (Atomic::cmpxchg(&_claimed_idx, current, current + stride) == current);
89 }
90 if (process_block) {
91 if (cb->is_alive()) {
92 f->do_code_blob(cb);
93 #ifdef ASSERT
94 if (cb->is_nmethod())
95 Universe::heap()->verify_nmethod((nmethod*)cb);
96 #endif
97 }
98 }
99 }
100
101 _finished = true;
102 }
103
104 ShenandoahNMethodTable* ShenandoahCodeRoots::_nmethod_table;
105 int ShenandoahCodeRoots::_disarmed_value = 1;
106
107 void ShenandoahCodeRoots::initialize() {
108 _nmethod_table = new ShenandoahNMethodTable();
109 }
110
111 void ShenandoahCodeRoots::register_nmethod(nmethod* nm) {
112 switch (ShenandoahCodeRootsStyle) {
113 case 0:
114 case 1:
115 break;
116 case 2: {
117 assert_locked_or_safepoint(CodeCache_lock);
118 _nmethod_table->register_nmethod(nm);
119 break;
120 }
121 default:
122 ShouldNotReachHere();
123 }
124 }
125
126 void ShenandoahCodeRoots::unregister_nmethod(nmethod* nm) {
127 switch (ShenandoahCodeRootsStyle) {
128 case 0:
129 case 1: {
130 break;
131 }
132 case 2: {
133 assert_locked_or_safepoint(CodeCache_lock);
134 _nmethod_table->unregister_nmethod(nm);
135 break;
136 }
137 default:
138 ShouldNotReachHere();
139 }
140 }
141
142 void ShenandoahCodeRoots::flush_nmethod(nmethod* nm) {
143 switch (ShenandoahCodeRootsStyle) {
144 case 0:
145 case 1: {
146 break;
147 }
148 case 2: {
149 assert_locked_or_safepoint(CodeCache_lock);
150 _nmethod_table->flush_nmethod(nm);
151 break;
152 }
153 default:
154 ShouldNotReachHere();
155 }
156 }
157
158 void ShenandoahCodeRoots::prepare_concurrent_unloading() {
159 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
160 _disarmed_value ++;
161 // 0 is reserved for new nmethod
162 if (_disarmed_value == 0) {
163 _disarmed_value = 1;
164 }
165
166 JavaThreadIteratorWithHandle jtiwh;
167 for (JavaThread *thr = jtiwh.next(); thr != NULL; thr = jtiwh.next()) {
168 ShenandoahThreadLocalData::set_disarmed_value(thr, _disarmed_value);
169 }
170 }
171
172 class ShenandoahNMethodUnlinkClosure : public NMethodClosure {
173 private:
174 bool _unloading_occurred;
175 volatile bool _failed;
176 ShenandoahHeap* _heap;
177
178 void set_failed() {
179 Atomic::store(&_failed, true);
180 }
181
182 void unlink(nmethod* nm) {
183 // Unlinking of the dependencies must happen before the
184 // handshake separating unlink and purge.
185 nm->flush_dependencies(false /* delete_immediately */);
186
187 // unlink_from_method will take the CompiledMethod_lock.
188 // In this case we don't strictly need it when unlinking nmethods from
189 // the Method, because it is only concurrently unlinked by
190 // the entry barrier, which acquires the per nmethod lock.
191 nm->unlink_from_method();
192
193 if (nm->is_osr_method()) {
194 // Invalidate the osr nmethod only once
195 nm->invalidate_osr_method();
196 }
197 }
198 public:
199 ShenandoahNMethodUnlinkClosure(bool unloading_occurred) :
200 _unloading_occurred(unloading_occurred),
201 _failed(false),
202 _heap(ShenandoahHeap::heap()) {}
203
204 virtual void do_nmethod(nmethod* nm) {
205 if (failed()) {
206 return;
207 }
208
209 ShenandoahNMethod* nm_data = ShenandoahNMethod::gc_data(nm);
210 assert(!nm_data->is_unregistered(), "Should not see unregistered entry");
211
212 if (!nm->is_alive()) {
213 return;
214 }
215
216 if (nm->is_unloading()) {
217 ShenandoahReentrantLocker locker(nm_data->lock());
218 unlink(nm);
219 return;
220 }
221
222 ShenandoahReentrantLocker locker(nm_data->lock());
223
224 // Heal oops and disarm
225 ShenandoahNMethod::heal_nmethod(nm);
226 ShenandoahNMethod::disarm_nmethod(nm);
227
228 // Clear compiled ICs and exception caches
229 if (!nm->unload_nmethod_caches(_unloading_occurred)) {
230 set_failed();
231 }
232 }
233
234 bool failed() const {
235 return Atomic::load(&_failed);
236 }
237 };
238
239 class ShenandoahUnlinkTask : public AbstractGangTask {
240 private:
241 ShenandoahNMethodUnlinkClosure _cl;
242 ICRefillVerifier* _verifier;
243 ShenandoahConcurrentNMethodIterator _iterator;
244
245 public:
246 ShenandoahUnlinkTask(bool unloading_occurred, ICRefillVerifier* verifier) :
247 AbstractGangTask("ShenandoahNMethodUnlinkTask"),
248 _cl(unloading_occurred),
249 _verifier(verifier),
250 _iterator(ShenandoahCodeRoots::table()) {
251 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
252 _iterator.nmethods_do_begin();
253 }
254
255 ~ShenandoahUnlinkTask() {
256 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
257 _iterator.nmethods_do_end();
258 }
259
260 virtual void work(uint worker_id) {
261 ShenandoahEvacOOMScope evac_scope;
262 ICRefillVerifierMark mark(_verifier);
263 _iterator.nmethods_do(&_cl);
264 }
265
266 bool success() const {
267 return !_cl.failed();
268 }
269 };
270
271 void ShenandoahCodeRoots::unlink(WorkGang* workers, bool unloading_occurred) {
272 assert(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
273 "Only when running concurrent class unloading");
274
275 for (;;) {
276 ICRefillVerifier verifier;
277
278 {
279 ShenandoahUnlinkTask task(unloading_occurred, &verifier);
280 workers->run_task(&task);
281 if (task.success()) {
282 return;
283 }
284 }
285
286 // Cleaning failed because we ran out of transitional IC stubs,
287 // so we have to refill and try again. Refilling requires taking
288 // a safepoint, so we temporarily leave the suspendible thread set.
289 SuspendibleThreadSetLeaver sts;
290 InlineCacheBuffer::refill_ic_stubs();
291 }
292 }
293
294 class ShenandoahNMethodPurgeClosure : public NMethodClosure {
295 public:
296 virtual void do_nmethod(nmethod* nm) {
297 if (nm->is_alive() && nm->is_unloading()) {
298 nm->make_unloaded();
299 }
300 }
301 };
302
303 class ShenandoahNMethodPurgeTask : public AbstractGangTask {
304 private:
305 ShenandoahNMethodPurgeClosure _cl;
306 ShenandoahConcurrentNMethodIterator _iterator;
307
308 public:
309 ShenandoahNMethodPurgeTask() :
310 AbstractGangTask("ShenandoahNMethodPurgeTask"),
311 _cl(),
312 _iterator(ShenandoahCodeRoots::table()) {
313 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
314 _iterator.nmethods_do_begin();
315 }
316
317 ~ShenandoahNMethodPurgeTask() {
318 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
319 _iterator.nmethods_do_end();
320 }
321
322 virtual void work(uint worker_id) {
323 _iterator.nmethods_do(&_cl);
324 }
325 };
326
327 void ShenandoahCodeRoots::purge(WorkGang* workers) {
328 assert(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
329 "Only when running concurrent class unloading");
330
331 ShenandoahNMethodPurgeTask task;
332 workers->run_task(&task);
333 }
334
335 ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
336 _par_iterator(CodeCache::heaps()),
337 _table_snapshot(NULL) {
338 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
339 assert(!Thread::current()->is_Worker_thread(), "Should not be acquired by workers");
340 switch (ShenandoahCodeRootsStyle) {
341 case 0:
342 case 1: {
343 // No need to do anything here
344 break;
345 }
346 case 2: {
347 CodeCache_lock->lock_without_safepoint_check();
348 _table_snapshot = ShenandoahCodeRoots::table()->snapshot_for_iteration();
349 break;
350 }
351 default:
352 ShouldNotReachHere();
353 }
354 }
355
356 ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
357 switch (ShenandoahCodeRootsStyle) {
358 case 0:
359 case 1: {
360 // No need to do anything here
361 break;
362 }
363 case 2: {
364 ShenandoahCodeRoots::table()->finish_iteration(_table_snapshot);
365 _table_snapshot = NULL;
366 CodeCache_lock->unlock();
367 break;
368 }
369 default:
370 ShouldNotReachHere();
371 }
372 }
373
374 template<bool CSET_FILTER>
375 void ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do(CodeBlobClosure *f) {
376 switch (ShenandoahCodeRootsStyle) {
377 case 0: {
378 if (_seq_claimed.try_set()) {
379 CodeCache::blobs_do(f);
380 }
381 break;
382 }
383 case 1: {
384 _par_iterator.parallel_blobs_do(f);
385 break;
386 }
387 case 2: {
388 ShenandoahCodeRootsIterator::fast_parallel_blobs_do<CSET_FILTER>(f);
389 break;
390 }
391 default:
392 ShouldNotReachHere();
393 }
394 }
395
396 void ShenandoahAllCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
397 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<false>(f);
398 }
399
400 void ShenandoahCsetCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
401 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<true>(f);
402 }
403
404 template <bool CSET_FILTER>
405 void ShenandoahCodeRootsIterator::fast_parallel_blobs_do(CodeBlobClosure *f) {
406 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
407 assert(_table_snapshot != NULL, "Sanity");
408 _table_snapshot->parallel_blobs_do<CSET_FILTER>(f);
409 }
410