Description:
Recursion in Dblqh::finishScanrec() triggers an assert in LocalDLFifoList<ScanRecord>() because there is an attempt to create two list iterators with the same head. This is a regression due to WL#7532 (Optimise NDB scans), which introduced this recursion.
The trace below shows the same list head is used in frame 13 and 41.
(gdb) frame 13
#13 0x0000000000732a21 in Dblqh::finishScanrec (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:12376
(gdb) p &fragptr.p->m_queuedScans
$3 = (IntrusiveList<Dblqh::ScanRecord, ArrayPool<Dblqh::ScanRecord>, ListHead<FirstLink, LastLink, NoCount>, DefaultDoubleLinkMethods<Dblqh::ScanRecord, Dblqh::ScanRecord> >::Head *) 0x2b12fb1a53b0
(gdb) frame 41
#41 0x0000000000733b96 in Dblqh::finishScanrec (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:12490
(gdb) p &fragptr.p->m_queuedScans
$4 = (IntrusiveList<Dblqh::ScanRecord, ArrayPool<Dblqh::ScanRecord>, ListHead<FirstLink, LastLink, NoCount>, DefaultDoubleLinkMethods<Dblqh::ScanRecord, Dblqh::ScanRecord> >::Head *) 0x2b12fb1a53b0
(gdb) where
#0 0x00002b12092b7425 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00002b12092bab8b in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2 0x0000000000435a09 in childAbort (error_code=6000, exit_code=-1, currentStartPhase=255) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/ndbd.cpp:425
#3 0x0000000000436835 in NdbShutdown (error_code=6000, type=NST_ErrorHandlerSignal, restartType=NRT_Default) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/ndbd.cpp:904
#4 0x0000000000af4da9 in ErrorReporter::handleError (messageID=6000, problemData=0x7fff572ad7a0 "Signal 6 received; Aborted", objRef=0xbdb3b0 "/export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/ndbd.cpp", nst=NST_ErrorHandlerSignal) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/error/ErrorReporter.cpp:257
#5 0x0000000000435bc0 in handler_error (signum=6) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/ndbd.cpp:473
#6 <signal handler called>
#7 0x00002b12092b7425 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#8 0x00002b12092bab8b in abort () from /lib/x86_64-linux-gnu/libc.so.6
#9 0x00002b12092b00ee in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#10 0x00002b12092b0192 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
#11 0x000000000079103f in IntrusiveList<Dblqh::ScanRecord, ArrayPool<Dblqh::ScanRecord>, ListHead<FirstLink, LastLink, NoCount>, DefaultDoubleLinkMethods<Dblqh::ScanRecord, Dblqh::ScanRecord> >::Local::Local (this=0x7fff572adea0, pool=..., head=...) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/vm/IntrusiveList.hpp:282
#12 0x000000000078f401 in LocalDLFifoList<Dblqh::ScanRecord, Dblqh::ScanRecord, DefaultDoubleLinkMethods<Dblqh::ScanRecord, Dblqh::ScanRecord> >::LocalDLFifoList (this=0x7fff572adea0, pool=..., head=...) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/vm/IntrusiveList.hpp:339
#13 0x0000000000732a21 in Dblqh::finishScanrec (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:12376
#14 0x00000000007315b0 in Dblqh::tupScanCloseConfLab (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:12093
#15 0x00000000007310c3 in Dblqh::accScanCloseConfLab (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:12064
#16 0x00000000007253ca in Dblqh::execNEXT_SCANCONF (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:9955
#17 0x000000000048c23c in SimulatedBlock::executeFunction (this=0x14aa5a0, gsn=330, signal=0x124dc00, f=(void (SimulatedBlock::*)(SimulatedBlock * const, Signal *)) 0x724e0e <Dblqh::execNEXT_SCANCONF(Signal*)>) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/vm/SimulatedBlock.hpp:1122
#18 0x000000000048c9aa in SimulatedBlock::EXECUTE_DIRECT (this=0x1488000, block=247, gsn=330, signal=0x124dc00, len=3) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/vm/SimulatedBlock.hpp:1429
#19 0x00000000004d4494 in Dbacc::releaseScanLab (this=0x1488000, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dbacc/DbaccMain.cpp:6492
#20 0x00000000004d26fb in Dbacc::execNEXT_SCANREQ (this=0x1488000, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dbacc/DbaccMain.cpp:6214
#21 0x000000000078bf43 in SimulatedBlock::EXECUTE_DIRECT (this=0x1488000, f=(void (SimulatedBlock::*)(SimulatedBlock * const, Signal *)) 0x4d1de6 <Dbacc::execNEXT_SCANREQ(Signal*)>, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/vm/SimulatedBlock.hpp:1317
#22 0x0000000000730db0 in Dblqh::closeScanLab (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:12023
#23 0x00000000007272e4 in Dblqh::scanLockReleasedLab (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:10209
#24 0x0000000000727bd1 in Dblqh::scanReleaseLocksLab (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:10340
#25 0x000000000072fba7 in Dblqh::scanTupkeyConfLab (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:11864
#26 0x00000000006f887b in Dblqh::execTUPKEYCONF (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:3657
#27 0x000000000072e227 in Dblqh::next_scanconf_tupkeyreq (this=0x14aa5a0, signal=0x124dc00, scanPtr=0x171d2b0, regTcPtr=0x2b12fb40aa10, fragPtrP=0x2b12fb1a5310, disk_page=4294967040) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:11661
#28 0x000000000072d69d in Dblqh::nextScanConfScanLab (this=0x14aa5a0, signal=0x124dc00, scanPtr=0x171d2b0, regTcPtr=0x2b12fb40aa10, fragId=0, accOpPtr=36096) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:11535
#29 0x000000000072550e in Dblqh::execNEXT_SCANCONF (this=0x14aa5a0, signal=0x124dc00) at /export/home/tmp/jw159207/mysql/repo/mysql-5.6-cluster-7.4/storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:9966
How to repeat:
Create database as shown below (full SQL script will be attached to bug), then run bencher as follows:
bencher -d ydb -e "select count(*) from t1 join t1 as t2 on t1.d<t2.c+2 join t1 as t3 on t2.d<t3.c+2 join t1 as t4 on t3.d<t4.c+2" -l 5 -t 32
drop database if exists ydb;
create database ydb;
use ydb;
CREATE TABLE t1 (
a int NOT NULL,
b int NOT NULL,
c int NOT NULL,
d int NOT NULL,
PRIMARY KEY (`b`,`a`)
) ENGINE=ndbcluster;
insert into t1 values (0, 1, 1, 1);
insert into t1 values (1, 1, 1, 2);
insert into t1 values (2, 1, 1, 3);
insert into t1 values (3, 1, 1, 4);
.
.
insert into t1 values (998, 1, 1, 999);
insert into t1 values (999, 1, 1, 0);
analyze table t1;
Suggested fix:
Add a release() method to LocalDLFifoList and related list types, such that it is possible to disconnect the LocalDLFifoList from a list head without running the destructor.
