Mercurial > hg > truffle
comparison src/share/vm/runtime/synchronizer.cpp @ 1640:bfc89697cccb
6964164: MonitorInUseLists leak of contended objects
Summary: fix MonitorInUseLists memory leak and MonitorBound now works
Reviewed-by: chrisphi, dice
author | acorn |
---|---|
date | Fri, 02 Jul 2010 17:23:43 -0400 |
parents | 3a9de63b2209 |
children | fa83ab460c54 |
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1627:c5f1ea9e15e8 | 1640:bfc89697cccb |
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745 // B. After adding an objectmonitor to a free list. | 745 // B. After adding an objectmonitor to a free list. |
746 // | 746 // |
747 | 747 |
748 ObjectMonitor * ObjectSynchronizer::gBlockList = NULL ; | 748 ObjectMonitor * ObjectSynchronizer::gBlockList = NULL ; |
749 ObjectMonitor * volatile ObjectSynchronizer::gFreeList = NULL ; | 749 ObjectMonitor * volatile ObjectSynchronizer::gFreeList = NULL ; |
750 ObjectMonitor * volatile ObjectSynchronizer::gOmInUseList = NULL ; | |
751 int ObjectSynchronizer::gOmInUseCount = 0; | |
750 static volatile intptr_t ListLock = 0 ; // protects global monitor free-list cache | 752 static volatile intptr_t ListLock = 0 ; // protects global monitor free-list cache |
751 static volatile int MonitorFreeCount = 0 ; // # on gFreeList | 753 static volatile int MonitorFreeCount = 0 ; // # on gFreeList |
752 static volatile int MonitorPopulation = 0 ; // # Extant -- in circulation | 754 static volatile int MonitorPopulation = 0 ; // # Extant -- in circulation |
753 #define CHAINMARKER ((oop)-1) | 755 #define CHAINMARKER ((oop)-1) |
754 | 756 |
824 ::printf ("Monitor scavenge - STW posted @%s (%d)\n", Whence, ForceMonitorScavenge) ; | 826 ::printf ("Monitor scavenge - STW posted @%s (%d)\n", Whence, ForceMonitorScavenge) ; |
825 ::fflush(stdout) ; | 827 ::fflush(stdout) ; |
826 } | 828 } |
827 } | 829 } |
828 } | 830 } |
831 /* Too slow for general assert or debug | |
832 void ObjectSynchronizer::verifyInUse (Thread *Self) { | |
833 ObjectMonitor* mid; | |
834 int inusetally = 0; | |
835 for (mid = Self->omInUseList; mid != NULL; mid = mid->FreeNext) { | |
836 inusetally ++; | |
837 } | |
838 assert(inusetally == Self->omInUseCount, "inuse count off"); | |
839 | |
840 int freetally = 0; | |
841 for (mid = Self->omFreeList; mid != NULL; mid = mid->FreeNext) { | |
842 freetally ++; | |
843 } | |
844 assert(freetally == Self->omFreeCount, "free count off"); | |
845 } | |
846 */ | |
829 | 847 |
830 ObjectMonitor * ATTR ObjectSynchronizer::omAlloc (Thread * Self) { | 848 ObjectMonitor * ATTR ObjectSynchronizer::omAlloc (Thread * Self) { |
831 // A large MAXPRIVATE value reduces both list lock contention | 849 // A large MAXPRIVATE value reduces both list lock contention |
832 // and list coherency traffic, but also tends to increase the | 850 // and list coherency traffic, but also tends to increase the |
833 // number of objectMonitors in circulation as well as the STW | 851 // number of objectMonitors in circulation as well as the STW |
851 guarantee (m->object() == NULL, "invariant") ; | 869 guarantee (m->object() == NULL, "invariant") ; |
852 if (MonitorInUseLists) { | 870 if (MonitorInUseLists) { |
853 m->FreeNext = Self->omInUseList; | 871 m->FreeNext = Self->omInUseList; |
854 Self->omInUseList = m; | 872 Self->omInUseList = m; |
855 Self->omInUseCount ++; | 873 Self->omInUseCount ++; |
874 // verifyInUse(Self); | |
875 } else { | |
876 m->FreeNext = NULL; | |
856 } | 877 } |
857 return m ; | 878 return m ; |
858 } | 879 } |
859 | 880 |
860 // 2: try to allocate from the global gFreeList | 881 // 2: try to allocate from the global gFreeList |
872 ObjectMonitor * take = gFreeList ; | 893 ObjectMonitor * take = gFreeList ; |
873 gFreeList = take->FreeNext ; | 894 gFreeList = take->FreeNext ; |
874 guarantee (take->object() == NULL, "invariant") ; | 895 guarantee (take->object() == NULL, "invariant") ; |
875 guarantee (!take->is_busy(), "invariant") ; | 896 guarantee (!take->is_busy(), "invariant") ; |
876 take->Recycle() ; | 897 take->Recycle() ; |
877 omRelease (Self, take) ; | 898 omRelease (Self, take, false) ; |
878 } | 899 } |
879 Thread::muxRelease (&ListLock) ; | 900 Thread::muxRelease (&ListLock) ; |
880 Self->omFreeProvision += 1 + (Self->omFreeProvision/2) ; | 901 Self->omFreeProvision += 1 + (Self->omFreeProvision/2) ; |
881 if (Self->omFreeProvision > MAXPRIVATE ) Self->omFreeProvision = MAXPRIVATE ; | 902 if (Self->omFreeProvision > MAXPRIVATE ) Self->omFreeProvision = MAXPRIVATE ; |
882 TEVENT (omFirst - reprovision) ; | 903 TEVENT (omFirst - reprovision) ; |
883 continue ; | |
884 | 904 |
885 const int mx = MonitorBound ; | 905 const int mx = MonitorBound ; |
886 if (mx > 0 && (MonitorPopulation-MonitorFreeCount) > mx) { | 906 if (mx > 0 && (MonitorPopulation-MonitorFreeCount) > mx) { |
887 // We can't safely induce a STW safepoint from omAlloc() as our thread | 907 // We can't safely induce a STW safepoint from omAlloc() as our thread |
888 // state may not be appropriate for such activities and callers may hold | 908 // state may not be appropriate for such activities and callers may hold |
959 // accumulation we could limit omCount to (omProvision*2), otherwise return | 979 // accumulation we could limit omCount to (omProvision*2), otherwise return |
960 // the objectMonitor to the global list. We should drain (return) in reasonable chunks. | 980 // the objectMonitor to the global list. We should drain (return) in reasonable chunks. |
961 // That is, *not* one-at-a-time. | 981 // That is, *not* one-at-a-time. |
962 | 982 |
963 | 983 |
964 void ObjectSynchronizer::omRelease (Thread * Self, ObjectMonitor * m) { | 984 void ObjectSynchronizer::omRelease (Thread * Self, ObjectMonitor * m, bool fromPerThreadAlloc) { |
965 guarantee (m->object() == NULL, "invariant") ; | 985 guarantee (m->object() == NULL, "invariant") ; |
966 m->FreeNext = Self->omFreeList ; | 986 |
967 Self->omFreeList = m ; | 987 // Remove from omInUseList |
968 Self->omFreeCount ++ ; | 988 if (MonitorInUseLists && fromPerThreadAlloc) { |
989 ObjectMonitor* curmidinuse = NULL; | |
990 for (ObjectMonitor* mid = Self->omInUseList; mid != NULL; ) { | |
991 if (m == mid) { | |
992 // extract from per-thread in-use-list | |
993 if (mid == Self->omInUseList) { | |
994 Self->omInUseList = mid->FreeNext; | |
995 } else if (curmidinuse != NULL) { | |
996 curmidinuse->FreeNext = mid->FreeNext; // maintain the current thread inuselist | |
997 } | |
998 Self->omInUseCount --; | |
999 // verifyInUse(Self); | |
1000 break; | |
1001 } else { | |
1002 curmidinuse = mid; | |
1003 mid = mid->FreeNext; | |
1004 } | |
1005 } | |
1006 } | |
1007 | |
1008 // FreeNext is used for both onInUseList and omFreeList, so clear old before setting new | |
1009 m->FreeNext = Self->omFreeList ; | |
1010 Self->omFreeList = m ; | |
1011 Self->omFreeCount ++ ; | |
969 } | 1012 } |
970 | 1013 |
971 // Return the monitors of a moribund thread's local free list to | 1014 // Return the monitors of a moribund thread's local free list to |
972 // the global free list. Typically a thread calls omFlush() when | 1015 // the global free list. Typically a thread calls omFlush() when |
973 // it's dying. We could also consider having the VM thread steal | 1016 // it's dying. We could also consider having the VM thread steal |
974 // monitors from threads that have not run java code over a few | 1017 // monitors from threads that have not run java code over a few |
975 // consecutive STW safepoints. Relatedly, we might decay | 1018 // consecutive STW safepoints. Relatedly, we might decay |
976 // omFreeProvision at STW safepoints. | 1019 // omFreeProvision at STW safepoints. |
1020 // | |
1021 // Also return the monitors of a moribund thread"s omInUseList to | |
1022 // a global gOmInUseList under the global list lock so these | |
1023 // will continue to be scanned. | |
977 // | 1024 // |
978 // We currently call omFlush() from the Thread:: dtor _after the thread | 1025 // We currently call omFlush() from the Thread:: dtor _after the thread |
979 // has been excised from the thread list and is no longer a mutator. | 1026 // has been excised from the thread list and is no longer a mutator. |
980 // That means that omFlush() can run concurrently with a safepoint and | 1027 // That means that omFlush() can run concurrently with a safepoint and |
981 // the scavenge operator. Calling omFlush() from JavaThread::exit() might | 1028 // the scavenge operator. Calling omFlush() from JavaThread::exit() might |
985 // operator. | 1032 // operator. |
986 | 1033 |
987 void ObjectSynchronizer::omFlush (Thread * Self) { | 1034 void ObjectSynchronizer::omFlush (Thread * Self) { |
988 ObjectMonitor * List = Self->omFreeList ; // Null-terminated SLL | 1035 ObjectMonitor * List = Self->omFreeList ; // Null-terminated SLL |
989 Self->omFreeList = NULL ; | 1036 Self->omFreeList = NULL ; |
990 if (List == NULL) return ; | |
991 ObjectMonitor * Tail = NULL ; | 1037 ObjectMonitor * Tail = NULL ; |
992 ObjectMonitor * s ; | |
993 int Tally = 0; | 1038 int Tally = 0; |
994 for (s = List ; s != NULL ; s = s->FreeNext) { | 1039 if (List != NULL) { |
995 Tally ++ ; | 1040 ObjectMonitor * s ; |
996 Tail = s ; | 1041 for (s = List ; s != NULL ; s = s->FreeNext) { |
997 guarantee (s->object() == NULL, "invariant") ; | 1042 Tally ++ ; |
998 guarantee (!s->is_busy(), "invariant") ; | 1043 Tail = s ; |
999 s->set_owner (NULL) ; // redundant but good hygiene | 1044 guarantee (s->object() == NULL, "invariant") ; |
1000 TEVENT (omFlush - Move one) ; | 1045 guarantee (!s->is_busy(), "invariant") ; |
1001 } | 1046 s->set_owner (NULL) ; // redundant but good hygiene |
1002 | 1047 TEVENT (omFlush - Move one) ; |
1003 guarantee (Tail != NULL && List != NULL, "invariant") ; | 1048 } |
1049 guarantee (Tail != NULL && List != NULL, "invariant") ; | |
1050 } | |
1051 | |
1052 ObjectMonitor * InUseList = Self->omInUseList; | |
1053 ObjectMonitor * InUseTail = NULL ; | |
1054 int InUseTally = 0; | |
1055 if (InUseList != NULL) { | |
1056 Self->omInUseList = NULL; | |
1057 ObjectMonitor *curom; | |
1058 for (curom = InUseList; curom != NULL; curom = curom->FreeNext) { | |
1059 InUseTail = curom; | |
1060 InUseTally++; | |
1061 } | |
1062 // TODO debug | |
1063 assert(Self->omInUseCount == InUseTally, "inuse count off"); | |
1064 Self->omInUseCount = 0; | |
1065 guarantee (InUseTail != NULL && InUseList != NULL, "invariant"); | |
1066 } | |
1067 | |
1004 Thread::muxAcquire (&ListLock, "omFlush") ; | 1068 Thread::muxAcquire (&ListLock, "omFlush") ; |
1005 Tail->FreeNext = gFreeList ; | 1069 if (Tail != NULL) { |
1006 gFreeList = List ; | 1070 Tail->FreeNext = gFreeList ; |
1007 MonitorFreeCount += Tally; | 1071 gFreeList = List ; |
1072 MonitorFreeCount += Tally; | |
1073 } | |
1074 | |
1075 if (InUseTail != NULL) { | |
1076 InUseTail->FreeNext = gOmInUseList; | |
1077 gOmInUseList = InUseList; | |
1078 gOmInUseCount += InUseTally; | |
1079 } | |
1080 | |
1008 Thread::muxRelease (&ListLock) ; | 1081 Thread::muxRelease (&ListLock) ; |
1009 TEVENT (omFlush) ; | 1082 TEVENT (omFlush) ; |
1010 } | 1083 } |
1011 | 1084 |
1012 | 1085 |
1164 ObjectMonitor * m = omAlloc (Self) ; | 1237 ObjectMonitor * m = omAlloc (Self) ; |
1165 // Optimistically prepare the objectmonitor - anticipate successful CAS | 1238 // Optimistically prepare the objectmonitor - anticipate successful CAS |
1166 // We do this before the CAS in order to minimize the length of time | 1239 // We do this before the CAS in order to minimize the length of time |
1167 // in which INFLATING appears in the mark. | 1240 // in which INFLATING appears in the mark. |
1168 m->Recycle(); | 1241 m->Recycle(); |
1169 m->FreeNext = NULL ; | |
1170 m->_Responsible = NULL ; | 1242 m->_Responsible = NULL ; |
1171 m->OwnerIsThread = 0 ; | 1243 m->OwnerIsThread = 0 ; |
1172 m->_recursions = 0 ; | 1244 m->_recursions = 0 ; |
1173 m->_SpinDuration = Knob_SpinLimit ; // Consider: maintain by type/class | 1245 m->_SpinDuration = Knob_SpinLimit ; // Consider: maintain by type/class |
1174 | 1246 |
1175 markOop cmp = (markOop) Atomic::cmpxchg_ptr (markOopDesc::INFLATING(), object->mark_addr(), mark) ; | 1247 markOop cmp = (markOop) Atomic::cmpxchg_ptr (markOopDesc::INFLATING(), object->mark_addr(), mark) ; |
1176 if (cmp != mark) { | 1248 if (cmp != mark) { |
1177 omRelease (Self, m) ; | 1249 omRelease (Self, m, true) ; |
1178 continue ; // Interference -- just retry | 1250 continue ; // Interference -- just retry |
1179 } | 1251 } |
1180 | 1252 |
1181 // We've successfully installed INFLATING (0) into the mark-word. | 1253 // We've successfully installed INFLATING (0) into the mark-word. |
1182 // This is the only case where 0 will appear in a mark-work. | 1254 // This is the only case where 0 will appear in a mark-work. |
1260 m->set_header(mark); | 1332 m->set_header(mark); |
1261 m->set_owner(NULL); | 1333 m->set_owner(NULL); |
1262 m->set_object(object); | 1334 m->set_object(object); |
1263 m->OwnerIsThread = 1 ; | 1335 m->OwnerIsThread = 1 ; |
1264 m->_recursions = 0 ; | 1336 m->_recursions = 0 ; |
1265 m->FreeNext = NULL ; | |
1266 m->_Responsible = NULL ; | 1337 m->_Responsible = NULL ; |
1267 m->_SpinDuration = Knob_SpinLimit ; // consider: keep metastats by type/class | 1338 m->_SpinDuration = Knob_SpinLimit ; // consider: keep metastats by type/class |
1268 | 1339 |
1269 if (Atomic::cmpxchg_ptr (markOopDesc::encode(m), object->mark_addr(), mark) != mark) { | 1340 if (Atomic::cmpxchg_ptr (markOopDesc::encode(m), object->mark_addr(), mark) != mark) { |
1270 m->set_object (NULL) ; | 1341 m->set_object (NULL) ; |
1271 m->set_owner (NULL) ; | 1342 m->set_owner (NULL) ; |
1272 m->OwnerIsThread = 0 ; | 1343 m->OwnerIsThread = 0 ; |
1273 m->Recycle() ; | 1344 m->Recycle() ; |
1274 omRelease (Self, m) ; | 1345 omRelease (Self, m, true) ; |
1275 m = NULL ; | 1346 m = NULL ; |
1276 continue ; | 1347 continue ; |
1277 // interference - the markword changed - just retry. | 1348 // interference - the markword changed - just retry. |
1278 // The state-transitions are one-way, so there's no chance of | 1349 // The state-transitions are one-way, so there's no chance of |
1279 // live-lock -- "Inflated" is an absorbing state. | 1350 // live-lock -- "Inflated" is an absorbing state. |
1850 // We have added a flag, MonitorInUseLists, which creates a list | 1921 // We have added a flag, MonitorInUseLists, which creates a list |
1851 // of active monitors for each thread. deflate_idle_monitors() | 1922 // of active monitors for each thread. deflate_idle_monitors() |
1852 // only scans the per-thread inuse lists. omAlloc() puts all | 1923 // only scans the per-thread inuse lists. omAlloc() puts all |
1853 // assigned monitors on the per-thread list. deflate_idle_monitors() | 1924 // assigned monitors on the per-thread list. deflate_idle_monitors() |
1854 // returns the non-busy monitors to the global free list. | 1925 // returns the non-busy monitors to the global free list. |
1926 // When a thread dies, omFlush() adds the list of active monitors for | |
1927 // that thread to a global gOmInUseList acquiring the | |
1928 // global list lock. deflate_idle_monitors() acquires the global | |
1929 // list lock to scan for non-busy monitors to the global free list. | |
1855 // An alternative could have used a single global inuse list. The | 1930 // An alternative could have used a single global inuse list. The |
1856 // downside would have been the additional cost of acquiring the global list lock | 1931 // downside would have been the additional cost of acquiring the global list lock |
1857 // for every omAlloc(). | 1932 // for every omAlloc(). |
1858 // | 1933 // |
1859 // Perversely, the heap size -- and thus the STW safepoint rate -- | 1934 // Perversely, the heap size -- and thus the STW safepoint rate -- |
1902 | 1977 |
1903 // Move the object to the working free list defined by FreeHead,FreeTail. | 1978 // Move the object to the working free list defined by FreeHead,FreeTail. |
1904 if (*FreeHeadp == NULL) *FreeHeadp = mid; | 1979 if (*FreeHeadp == NULL) *FreeHeadp = mid; |
1905 if (*FreeTailp != NULL) { | 1980 if (*FreeTailp != NULL) { |
1906 ObjectMonitor * prevtail = *FreeTailp; | 1981 ObjectMonitor * prevtail = *FreeTailp; |
1982 assert(prevtail->FreeNext == NULL, "cleaned up deflated?"); // TODO KK | |
1907 prevtail->FreeNext = mid; | 1983 prevtail->FreeNext = mid; |
1908 } | 1984 } |
1909 *FreeTailp = mid; | 1985 *FreeTailp = mid; |
1910 deflated = true; | 1986 deflated = true; |
1911 } | 1987 } |
1912 return deflated; | 1988 return deflated; |
1989 } | |
1990 | |
1991 // Caller acquires ListLock | |
1992 int ObjectSynchronizer::walk_monitor_list(ObjectMonitor** listheadp, | |
1993 ObjectMonitor** FreeHeadp, ObjectMonitor** FreeTailp) { | |
1994 ObjectMonitor* mid; | |
1995 ObjectMonitor* next; | |
1996 ObjectMonitor* curmidinuse = NULL; | |
1997 int deflatedcount = 0; | |
1998 | |
1999 for (mid = *listheadp; mid != NULL; ) { | |
2000 oop obj = (oop) mid->object(); | |
2001 bool deflated = false; | |
2002 if (obj != NULL) { | |
2003 deflated = deflate_monitor(mid, obj, FreeHeadp, FreeTailp); | |
2004 } | |
2005 if (deflated) { | |
2006 // extract from per-thread in-use-list | |
2007 if (mid == *listheadp) { | |
2008 *listheadp = mid->FreeNext; | |
2009 } else if (curmidinuse != NULL) { | |
2010 curmidinuse->FreeNext = mid->FreeNext; // maintain the current thread inuselist | |
2011 } | |
2012 next = mid->FreeNext; | |
2013 mid->FreeNext = NULL; // This mid is current tail in the FreeHead list | |
2014 mid = next; | |
2015 deflatedcount++; | |
2016 } else { | |
2017 curmidinuse = mid; | |
2018 mid = mid->FreeNext; | |
2019 } | |
2020 } | |
2021 return deflatedcount; | |
1913 } | 2022 } |
1914 | 2023 |
1915 void ObjectSynchronizer::deflate_idle_monitors() { | 2024 void ObjectSynchronizer::deflate_idle_monitors() { |
1916 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); | 2025 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); |
1917 int nInuse = 0 ; // currently associated with objects | 2026 int nInuse = 0 ; // currently associated with objects |
1927 // And in case the vm thread is acquiring a lock during a safepoint | 2036 // And in case the vm thread is acquiring a lock during a safepoint |
1928 // See e.g. 6320749 | 2037 // See e.g. 6320749 |
1929 Thread::muxAcquire (&ListLock, "scavenge - return") ; | 2038 Thread::muxAcquire (&ListLock, "scavenge - return") ; |
1930 | 2039 |
1931 if (MonitorInUseLists) { | 2040 if (MonitorInUseLists) { |
1932 ObjectMonitor* mid; | 2041 int inUse = 0; |
1933 ObjectMonitor* next; | |
1934 ObjectMonitor* curmidinuse; | |
1935 for (JavaThread* cur = Threads::first(); cur != NULL; cur = cur->next()) { | 2042 for (JavaThread* cur = Threads::first(); cur != NULL; cur = cur->next()) { |
1936 curmidinuse = NULL; | 2043 nInCirculation+= cur->omInUseCount; |
1937 for (mid = cur->omInUseList; mid != NULL; ) { | 2044 int deflatedcount = walk_monitor_list(cur->omInUseList_addr(), &FreeHead, &FreeTail); |
1938 oop obj = (oop) mid->object(); | 2045 cur->omInUseCount-= deflatedcount; |
1939 deflated = false; | 2046 // verifyInUse(cur); |
1940 if (obj != NULL) { | 2047 nScavenged += deflatedcount; |
1941 deflated = deflate_monitor(mid, obj, &FreeHead, &FreeTail); | 2048 nInuse += cur->omInUseCount; |
1942 } | |
1943 if (deflated) { | |
1944 // extract from per-thread in-use-list | |
1945 if (mid == cur->omInUseList) { | |
1946 cur->omInUseList = mid->FreeNext; | |
1947 } else if (curmidinuse != NULL) { | |
1948 curmidinuse->FreeNext = mid->FreeNext; // maintain the current thread inuselist | |
1949 } | |
1950 next = mid->FreeNext; | |
1951 mid->FreeNext = NULL; // This mid is current tail in the FreeHead list | |
1952 mid = next; | |
1953 cur->omInUseCount--; | |
1954 nScavenged ++ ; | |
1955 } else { | |
1956 curmidinuse = mid; | |
1957 mid = mid->FreeNext; | |
1958 nInuse ++; | |
1959 } | |
1960 } | 2049 } |
1961 } | 2050 |
2051 // For moribund threads, scan gOmInUseList | |
2052 if (gOmInUseList) { | |
2053 nInCirculation += gOmInUseCount; | |
2054 int deflatedcount = walk_monitor_list((ObjectMonitor **)&gOmInUseList, &FreeHead, &FreeTail); | |
2055 gOmInUseCount-= deflatedcount; | |
2056 nScavenged += deflatedcount; | |
2057 nInuse += gOmInUseCount; | |
2058 } | |
2059 | |
1962 } else for (ObjectMonitor* block = gBlockList; block != NULL; block = next(block)) { | 2060 } else for (ObjectMonitor* block = gBlockList; block != NULL; block = next(block)) { |
1963 // Iterate over all extant monitors - Scavenge all idle monitors. | 2061 // Iterate over all extant monitors - Scavenge all idle monitors. |
1964 assert(block->object() == CHAINMARKER, "must be a block header"); | 2062 assert(block->object() == CHAINMARKER, "must be a block header"); |
1965 nInCirculation += _BLOCKSIZE ; | 2063 nInCirculation += _BLOCKSIZE ; |
1966 for (int i = 1 ; i < _BLOCKSIZE; i++) { | 2064 for (int i = 1 ; i < _BLOCKSIZE; i++) { |