We are using LMDB and are running a big number of tests on a CI server (Debian via Docker, Xenon CPU).   The crash happens during opening the database. This is done a lot in the tests without problems (and on Windows this problem does not exist). However, during the CI process we get the crash quite reproducible (~80% crash rate when running the full CI test suite).

This is our basic code triggering the SIGSEGV (minus error checking for simplicity):

mdb_env_create(&dbEnv_);     mdb_env_set_maxdbs(dbEnv_, 8);     mdb_env_set_mapsize(dbEnv_, maxDbSizeInKByte * 1024);     mdb_env_open(dbEnv_, directory, 0, fileMode);     MDB_txn* txn;     mdb_txn_begin(dbEnv_, NULL, 0, &txn);   It crashes inside mdb_txn_begin with this: SIGSEGV (0xb) at pc=0x00007fd2607e4b58, pid=23603, tid=0x00007fd228633700 C [libpthread.so.0+0x5b58] __pthread_mutex_lock_full+0x1a8   I digged into it a bit, and could tracd it down to this LOCK_MUTEX call in mdb_txn_renew0:           /* Not yet touching txn == env->me_txn0, it may be active */         if (ti) {             if (LOCK_MUTEX(rc, env, env->me_wmutex))                 return rc;

I also logged some data about the env and the mutex (which looks normal however): PID: 23603 ENV: 0x7fd1e03e9ab0 TXN: 0x7fd22811b000 COUNT: 0 KIND: 144 LOCK: 0 OWNER: 0

Any idea what could go wrong here?   Thanks! Markus

Some additional crash info:

siginfo: si_signo: 11 (SIGSEGV), si_code: 1 (SEGV_MAPERR), si_addr: 0x00007fd22801a058

Registers: RAX=0x00007fd22801a060, RBX=0x00007fd22811b040, RCX=0x0000000000000000, RDX=0x0000000000000000 RSP=0x00007fd22862ff50, RBP=0x0000000000005c4f, RSI=0x0000000000000080, RDI=0x0000000000005c4f R8 =0x0000000000000080, R9 =0x0000000000000000, R10=0x00007fd22811b060, R11=0x0000000000000000 R12=0x0000000000000000, R13=0x00007fd22813b0f0, R14=0x00007fd2286309d0, R15=0x00007fd25848b000 RIP=0x00007fd2607e4b58, EFLAGS=0x0000000000010206, CSGSFS=0x0000000000000033, ERR=0x0000000000000006 TRAPNO=0x000000000000000e

Top of Stack: (sp=0x00007fd22862ff50) 0x00007fd22862ff50: 00007fd22813b0f0 00007fd228630040 0x00007fd22862ff60: 0000000000000000 00007fd22813b0f0 0x00007fd22862ff70: 00007fd2286309d0 00007fd20c2d05e4 0x00007fd22862ff80: 00007fd228630050 00007fd22862ff90 0x00007fd22862ff90: 0000000000001020 000000000000003c 0x00007fd22862ffa0: 0000000a00000023 0000000a00000000 0x00007fd22862ffb0: 00007fd228633700 00007fd25fee1c29 0x00007fd22862ffc0: 0000000000000000 00007fd25fe7a423 0x00007fd22862ffd0: 00007fd2286309d0 0000000900000000 0x00007fd22862ffe0: 0000000000000008 00007fd244000000 0x00007fd22862fff0: 00007fd22813b0f0 00007fd25fe79ae3 0x00007fd228630000: 0000000000000000 00000000286300c0 0x00007fd228630010: 0000000000000000 00007fd25fe7b255 0x00007fd228630020: 00007fd22811b000 00007fd1e03e9ab0 0x00007fd228630030: 00007fd1e08f3260 00007fd25fe6fb22 0x00007fd228630040: 00007fd2286300c0 00007fd20c2d0e8a 0x00007fd228630050: 00007fd2286300c0 00007fd2601ac2a0 0x00007fd228630060: 0000000000000020 00007fd244000000 0x00007fd228630070: 0000000800000000 00007fd25fe79ae3 0x00007fd228630080: 0000000000000020 00007fd228630660 0x00007fd228630090: 00007fd1e08f3260 00007fd2286301c8 0x00007fd2286300a0: 00000000601ac2a0 0000000000000000 0x00007fd2286300b0: 00007fd1e03e9ab0 00007fd25fe6fb22 0x00007fd2286300c0: 00007fd228630660 00007fd20c23a768 0x00007fd2286300d0: 0000000200f01b00 00007fd20000003b 0x00007fd2286300e0: 00007fd20c2eb3fd 00007fd24921da4c 0x00007fd2286300f0: 00000005cac01420 00007fd22814c210 0x00007fd228630100: 00007fd228630460 00007fd24921f99f 0x00007fd228630110: 00007fd2286301c8 0000002000000000 0x00007fd228630120: 0000000000000000 0000000000000000 0x00007fd228630130: 0000000000000000 0000000000000020 0x00007fd228630140: 0000000000000000 0000000000000000

Instructions: (pc=0x00007fd2607e4b58) 0x00007fd2607e4b38: 00 a9 00 00 00 40 0f 85 02 ff ff ff c7 43 04 01 0x00007fd2607e4b48: 00 00 00 64 48 8b 04 25 e0 02 00 00 48 83 e0 fe 0x00007fd2607e4b58: 4c 89 50 f8 64 48 8b 04 25 e0 02 00 00 48 89 43 0x00007fd2607e4b68: 20 64 48 8b 04 25 10 00 00 00 48 05 e0 02 00 00

Register to memory mapping:

RAX=0x00007fd22801a060 is an unknown value RBX=0x00007fd22811b040 is an unknown value RCX=0x0000000000000000 is an unknown value RDX=0x0000000000000000 is an unknown value RSP=0x00007fd22862ff50 is pointing into the stack for thread: 0x00007fd25848b000 RBP=0x0000000000005c4f is an unknown value RSI=0x0000000000000080 is an unknown value RDI=0x0000000000005c4f is an unknown value R8 =0x0000000000000080 is an unknown value R9 =0x0000000000000000 is an unknown value R10=0x00007fd22811b060 is an unknown value R11=0x0000000000000000 is an unknown value R12=0x0000000000000000 is an unknown value R13={method} {0x00007fd22813b0f0} 'nativeCreate' '(Ljava/lang/String;J[B)J' in 'MyDb' R14=0x00007fd2286309d0 is pointing into the stack for thread: 0x00007fd25848b000 R15=0x00007fd25848b000 is a thread