11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27
28 #include "cds/aotMappedHeapWriter.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "gc/shared/classUnloadingContext.hpp"
31 #include "gc/shared/fullGCForwarding.hpp"
32 #include "gc/shared/gc_globals.hpp"
33 #include "gc/shared/gcArguments.hpp"
34 #include "gc/shared/gcTimer.hpp"
35 #include "gc/shared/gcTraceTime.inline.hpp"
36 #include "gc/shared/locationPrinter.inline.hpp"
37 #include "gc/shared/memAllocator.hpp"
38 #include "gc/shared/plab.hpp"
39 #include "gc/shared/tlab_globals.hpp"
40 #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp"
41 #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp"
42 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
43 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
44 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
45 #include "gc/shenandoah/shenandoahAllocRate.inline.hpp"
46 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
47 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
48 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
49 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
50 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
51 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
1284 Handshake::execute(&composite);
1285 }
1286 }
1287
1288 oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
1289 assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
1290
1291 ShenandoahHeapRegion* r = heap_region_containing(p);
1292 assert(!r->is_humongous(), "never evacuate humongous objects");
1293
1294 ShenandoahAffiliation target_gen = r->affiliation();
1295 return try_evacuate_object(p, thread, r, target_gen);
1296 }
1297
1298 oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region,
1299 ShenandoahAffiliation target_gen) {
1300 assert(target_gen == YOUNG_GENERATION, "Only expect evacuations to young in this mode");
1301 assert(from_region->is_young(), "Only expect evacuations from young in this mode");
1302 bool alloc_from_lab = true;
1303 HeapWord* copy = nullptr;
1304 size_t size = ShenandoahForwarding::size(p);
1305
1306 #ifdef ASSERT
1307 if (ShenandoahOOMDuringEvacALot &&
1308 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
1309 copy = nullptr;
1310 } else {
1311 #endif
1312 if (UseTLAB) {
1313 copy = allocate_from_gclab(thread, size);
1314 }
1315 if (copy == nullptr) {
1316 // If we failed to allocate in LAB, we'll try a shared allocation.
1317 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen);
1318 copy = allocate_memory(req);
1319 alloc_from_lab = false;
1320 }
1321 #ifdef ASSERT
1322 }
1323 #endif
1324
1331 // (they succeeded where we failed) or self-forwarded first.
1332 markWord old_mark = p->mark();
1333 if (old_mark.is_forwarded()) {
1334 return ShenandoahForwarding::get_forwardee(p);
1335 }
1336 oop winner = ShenandoahForwarding::try_forward_to_self(p, old_mark);
1337 if (winner == nullptr) {
1338 // We own the self-forwarding. Flag the region so the degen/full GC
1339 // entry drain knows to scan it for self_fwd bits to clear.
1340 from_region->set_has_self_forwards();
1341 return p;
1342 }
1343 return winner;
1344 }
1345
1346 if (ShenandoahEvacTracking) {
1347 evac_tracker()->begin_evacuation(thread, size * HeapWordSize, from_region->affiliation(), target_gen);
1348 }
1349
1350 // Copy the object:
1351 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
1352
1353 oop copy_val = cast_to_oop(copy);
1354
1355 // Relativize stack chunks before publishing the copy. After the forwarding CAS,
1356 // mutators can see the copy and thaw it via the fast path if flags == 0. We must
1357 // relativize derived pointers and set gc_mode before that happens. Skip if the
1358 // copy's mark word is already a forwarding pointer (another thread won the race
1359 // and overwrote the original's header before we copied it).
1360 if (!ShenandoahForwarding::is_forwarded(copy_val)) {
1361 ContinuationGCSupport::relativize_stack_chunk(copy_val);
1362 }
1363
1364 // Try to install the new forwarding pointer.
1365 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
1366 if (result == copy_val) {
1367 // Successfully evacuated. Our copy is now the public one!
1368 shenandoah_assert_correct(nullptr, copy_val);
1369 if (ShenandoahEvacTracking) {
1370 evac_tracker()->end_evacuation(thread, size * HeapWordSize, from_region->affiliation(), target_gen);
1371 }
1372 return copy_val;
1373 } else {
1374 // Failed to evacuate. We need to deal with the object that is left behind. Since this
|
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27
28 #include "cds/aotMappedHeapWriter.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "gc/shared/classUnloadingContext.hpp"
31 #include "gc/shared/fullGCForwarding.inline.hpp"
32 #include "gc/shared/gc_globals.hpp"
33 #include "gc/shared/gcArguments.hpp"
34 #include "gc/shared/gcTimer.hpp"
35 #include "gc/shared/gcTraceTime.inline.hpp"
36 #include "gc/shared/locationPrinter.inline.hpp"
37 #include "gc/shared/memAllocator.hpp"
38 #include "gc/shared/plab.hpp"
39 #include "gc/shared/tlab_globals.hpp"
40 #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp"
41 #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp"
42 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
43 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
44 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
45 #include "gc/shenandoah/shenandoahAllocRate.inline.hpp"
46 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
47 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
48 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
49 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
50 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
51 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
1284 Handshake::execute(&composite);
1285 }
1286 }
1287
1288 oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
1289 assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
1290
1291 ShenandoahHeapRegion* r = heap_region_containing(p);
1292 assert(!r->is_humongous(), "never evacuate humongous objects");
1293
1294 ShenandoahAffiliation target_gen = r->affiliation();
1295 return try_evacuate_object(p, thread, r, target_gen);
1296 }
1297
1298 oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region,
1299 ShenandoahAffiliation target_gen) {
1300 assert(target_gen == YOUNG_GENERATION, "Only expect evacuations to young in this mode");
1301 assert(from_region->is_young(), "Only expect evacuations from young in this mode");
1302 bool alloc_from_lab = true;
1303 HeapWord* copy = nullptr;
1304
1305 markWord mark = p->mark();
1306 if (mark.is_forwarded()) {
1307 return ShenandoahForwarding::get_forwardee(p);
1308 }
1309 size_t old_size = ShenandoahForwarding::size(p);
1310 size_t size = p->copy_size(old_size, mark);
1311
1312 #ifdef ASSERT
1313 if (ShenandoahOOMDuringEvacALot &&
1314 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
1315 copy = nullptr;
1316 } else {
1317 #endif
1318 if (UseTLAB) {
1319 copy = allocate_from_gclab(thread, size);
1320 }
1321 if (copy == nullptr) {
1322 // If we failed to allocate in LAB, we'll try a shared allocation.
1323 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen);
1324 copy = allocate_memory(req);
1325 alloc_from_lab = false;
1326 }
1327 #ifdef ASSERT
1328 }
1329 #endif
1330
1337 // (they succeeded where we failed) or self-forwarded first.
1338 markWord old_mark = p->mark();
1339 if (old_mark.is_forwarded()) {
1340 return ShenandoahForwarding::get_forwardee(p);
1341 }
1342 oop winner = ShenandoahForwarding::try_forward_to_self(p, old_mark);
1343 if (winner == nullptr) {
1344 // We own the self-forwarding. Flag the region so the degen/full GC
1345 // entry drain knows to scan it for self_fwd bits to clear.
1346 from_region->set_has_self_forwards();
1347 return p;
1348 }
1349 return winner;
1350 }
1351
1352 if (ShenandoahEvacTracking) {
1353 evac_tracker()->begin_evacuation(thread, size * HeapWordSize, from_region->affiliation(), target_gen);
1354 }
1355
1356 // Copy the object:
1357 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, old_size);
1358 oop copy_val = cast_to_oop(copy);
1359
1360 // Initialize the identity hash on the copy before installing the forwarding
1361 // pointer, using the mark word we captured earlier. We must do this before
1362 // the CAS so that the copy is fully initialized when it becomes visible to
1363 // other threads. Using the captured mark (rather than re-reading the copy's
1364 // mark) avoids races with other threads that may have evacuated p and
1365 // installed a forwarding pointer in the meantime.
1366 if (UseCompactObjectHeaders && mark.is_hashed_not_expanded()) {
1367 copy_val->set_mark(copy_val->initialize_hash_if_necessary(p, mark.klass(), mark));
1368 }
1369
1370 // Relativize stack chunks before publishing the copy. After the forwarding CAS,
1371 // mutators can see the copy and thaw it via the fast path if flags == 0. We must
1372 // relativize derived pointers and set gc_mode before that happens. Skip if the
1373 // copy's mark word is already a forwarding pointer (another thread won the race
1374 // and overwrote the original's header before we copied it).
1375 if (!ShenandoahForwarding::is_forwarded(copy_val)) {
1376 ContinuationGCSupport::relativize_stack_chunk(copy_val);
1377 }
1378
1379 // Try to install the new forwarding pointer.
1380 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
1381 if (result == copy_val) {
1382 // Successfully evacuated. Our copy is now the public one!
1383 shenandoah_assert_correct(nullptr, copy_val);
1384 if (ShenandoahEvacTracking) {
1385 evac_tracker()->end_evacuation(thread, size * HeapWordSize, from_region->affiliation(), target_gen);
1386 }
1387 return copy_val;
1388 } else {
1389 // Failed to evacuate. We need to deal with the object that is left behind. Since this
|