Hi,
My program uses 1 write connection, 3 read connections. SQLite is open as "`SQLITE_OPEN_NOMUTEX`".
When a thread needs to access the SQLite, it needs to get a connection by waiting on a condition variable. So effectively once a thread waited successfully, it exclusively owns that connection object.
If a thread wants the write connection, it needs to wait until no read connection is busy, and once write connection is busy, no read connection can be retrieved.
It's been running a while on MacOS, Windows and QNX without problem.
Yesterday I run the program in linux docker containers, some mysterious crash happened.
One is centos 7 container:
statement is:
`"SELECT \"tile_blob\" FROM \"tiles_table\"\n WHERE \"tile_meta\" = @tile_meta AND \"tile_id\" = @tile_id;"`
Call stack:
```
Program terminated with signal 11, Segmentation fault.
#0 0x0000000000806ad2 in sqlite3VdbeAddOp3 (p=0x7f84d00279e8, op=96, p1=0, p2=4, p3=0) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:77795
77795 /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c: No such file or directory.
warning: File "/usr/local/lib64/libstdc++.so.6.0.22-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load:/usr/bin/mono-gdb.py".
To enable execution of this file add
add-auto-load-safe-path /usr/local/lib64/libstdc++.so.6.0.22-gdb.py
line to your configuration file "/root/.gdbinit".
To completely disable this security protection add
set auto-load safe-path /
line to your configuration file "/root/.gdbinit".
For more information about this security protection see the
"Auto-loading safe path" section in the GDB manual. E.g., run from the shell:
info "(gdb)Auto-loading safe path"
Missing separate debuginfos, use: debuginfo-install glibc-2.17-292.el7.x86_64 keyutils-libs-1.5.8-3.el7.x86_64 krb5-libs-1.15.1-37.el7_7.2.x86_64 libcom_err-1.42.9-16.el7.x86_64 libselinux-2.5-14.1.el7.x86_64 openssl-libs-1.0.2k-19.el7.x86_64 pcre-8.32-17.el7.x86_64 zlib-1.2.7-18.el7.x86_64
(gdb) bt
#0 0x0000000000806ad2 in sqlite3VdbeAddOp3 (p=0x7f84d00279e8, op=96, p1=0, p2=4, p3=0) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:77795
#1 0x000000000080728f in sqlite3VdbeAddOp4Int (p=0x7f84d00279e8, op=96, p1=0, p2=4, p3=0, p4=5) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:78040
#2 0x0000000000846b94 in sqlite3OpenTable (pParse=0x7ffd1e0d6ab0, iCur=0, iDb=0, pTab=0x7f84dc016778, opcode=96) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:120293
#3 0x000000000087877c in sqlite3WhereBegin (pParse=0x7ffd1e0d6ab0, pTabList=0x7f84d002afc8, pWhere=0x7f84d002ad48, pOrderBy=0x0, pResultSet=0x7f84d002aac8, wctrlFlags=0, iAuxArg=320)
at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:150096
#4 0x000000000085e8f3 in sqlite3Select (pParse=0x7ffd1e0d6ab0, p=0x7f84d002af48, pDest=0x7ffd1e0d5e70) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:135208
#5 0x00000000008803fd in yy_reduce (yypParser=0x7ffd1e0d60c0, yyruleno=82, yyLookahead=1, yyLookaheadToken=..., pParse=0x7ffd1e0d6ab0) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:157152
#6 0x0000000000884586 in sqlite3Parser (yyp=0x7ffd1e0d60c0, yymajor=1, yyminor=...) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:158453
#7 0x000000000088576b in sqlite3RunParser (pParse=0x7ffd1e0d6ab0, zSql=0x149f253 ";", pzErrMsg=0x7ffd1e0d6c58) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:159732
#8 0x00000000008531e8 in sqlite3Prepare (db=0x7f84d001d0c8, zSql=0x149f1f0 "SELECT \"tile_blob\" FROM \"tiles_hd_8590\"\n WHERE \"tile_meta\" = @tile_meta AND \"tile_id\" = @tile_id;", nBytes=101, prepFlags=128, pReprepare=0x0, ppStmt=0x7ffd1e0d6ea8, pzTail=0x0)
at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:128665
#9 0x0000000000853410 in sqlite3LockAndPrepare (db=0x7f84d001d0c8, zSql=0x149f1f0 "SELECT \"tile_blob\" FROM \"tiles_hd_8590\"\n WHERE \"tile_meta\" = @tile_meta AND \"tile_id\" = @tile_id;", nBytes=101, prepFlags=128, pOld=0x0, ppStmt=0x7ffd1e0d6ea8, pzTail=0x0)
at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:128737
#10 0x00000000008535e6 in sqlite3_prepare_v2 (db=0x7f84d001d0c8, zSql=0x149f1f0 "SELECT \"tile_blob\" FROM \"tiles_hd_8590\"\n WHERE \"tile_meta\" = @tile_meta AND \"tile_id\" = @tile_id;", nBytes=101, ppStmt=0x7ffd1e0d6ea8, pzTail=0x0)
at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-centos7x64/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:128821
```
Another is Ubuntu 1804 container, statement is:
statement is
`"SELECT \"tile_blob\" FROM \"tiles_table\"\n WHERE \"tile_meta\" = @tile_meta AND \"tile_id\" = @tile_id;"`
``
Call stack:
```
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `./ft -ns -tc=... ...'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007eff04f84b03 in sqlite3ApiExit (db=0x40000000000, rc=0) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-ubuntu-1804/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:28090
28090 /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-ubuntu-1804/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c: No such file or directory.
[Current thread is 1 (Thread 0x7eff04b35900 (LWP 47426))]
(gdb) bt
#0 0x00007eff04f84b03 in sqlite3ApiExit (db=0x40000000000, rc=0) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-ubuntu-1804/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:28090
#1 0x00007eff04fbc772 in sqlite3Step (p=0x7efee4026d78) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-ubuntu-1804/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:83508
#2 0x00007eff04fbc913 in sqlite3_step (pStmt=0x7efee4026d78) at /home/jenkins/agent/workspace/nav/thirdparty/develop/linux-ubuntu-1804/thirdparty/sqlite/sqlite-amalgamation/sqlite3.c:83553
```
The "sqlite-amalgamation" used to build SQLite is:
```
#define SQLITE_VERSION "3.32.3"
#define SQLITE_VERSION_NUMBER 3032003
#define SQLITE_SOURCE_ID "2020-06-18 14:00:33 7ebdfa80be8e8e73324b8d66b3460222eb74c7e9dfd655b48d6ca7e1933cc8fd"
```
Is there any suggestion to help me to pinpoint the problem?
Thanks.