Re: (ITS#9155) LMDB: List of spill pages leaks after transaction

[hyc@symas.com]

babayants.alexander@gmail.com wrote:
> Full_Name: Alexander Babayants
> Version: LMDB 0.9.24
> OS: Linux
> URL: ftp://ftp.openldap.org/incoming/
> Submission from: (NULL) (188.170.78.53)
> 
> 
> Hi!
> 
> ASAN shows that the list of spill pages is not freed after transaction:

Thanks for the report. Fixed now in mdb.master and mdb.RE/0.9

> =================================================================
> ==test==13046==ERROR: LeakSanitizer: detected memory leaks
> 
> Direct leak of 20971376 byte(s) in 1 object(s) allocated from:
>     #0 0x4bcbb2 in realloc (test+0x4bcbb2)
>     #1 0x7f067ef5ed59 in mdb_midl_grow liblmdb/src/midl.c:135:8
>     #2 0x7f067ef5ec83 in mdb_midl_append liblmdb/src/midl.c:162:7
>     #3 0x7f067ef4456b in mdb_page_spill liblmdb/src/mdb.c:2077:13
>     #4 0x7f067ef3960b in mdb_cursor_put liblmdb/src/mdb.c:6640:14
>     #5 0x7f067ef5106c in mdb_put liblmdb/src/mdb.c:9027:7
>     #6 0x4ec674 in main test.c:28:14
>     #7 0x7f067b46d544 in __libc_start_main (/lib64/libc.so.6+0x22544)
> 
> SUMMARY: AddressSanitizer: 20971376 byte(s) leaked in 1 allocation(s).
> 
> Reproducible on LMDB 0.9.24 with the following code (anything doing
> long write transaction will trigger this):
> #include "lmdb.h"
> 
> int main(int argc,char * argv[])
> {
>     int rc;
>     MDB_env *env;
>     MDB_dbi dbi;
>     MDB_val key, data;
>     MDB_txn *txn;
>     int kval;
>     char sval[1024] = {0}; // fine to fill with zeroes
> 
>     rc = mdb_env_create(&env);
>     rc = mdb_env_set_mapsize(env, 10ULL * 1024 * 1024 * 1024); // 10 GiB
>     rc = mdb_env_open(env, "./testdb", 0, 0664);
>     rc = mdb_txn_begin(env, NULL, 0, &txn);
>     rc = mdb_dbi_open(txn, NULL, 0, &dbi);
> 
>     key.mv_size = sizeof(int);
>     key.mv_data = &kval;
>     data.mv_size = sizeof(sval);
>     data.mv_data = sval;
> 
>     for (kval = 0; kval < 100'000'000; ++kval) {
>         rc = mdb_put(txn, dbi, &key, &data, 0);
>     }
>     rc = mdb_txn_commit(txn);
> 
>     mdb_dbi_close(env, dbi);
>     mdb_env_close(env);
>     return 0;
> }
> 
>>From my point of view the leak looks benign (=does not lead to
> database corruption or such), but I didn't dive deep enough in LMDB
> internals to be completely certain about that.
> 
> Regards,
> Alexander Babayants.
> 
> 


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