Hello I do not have clear examples to post on this but would like to report findings around multi threaded read access (single process) in a large system that uses sqlite.
This may be a known issue/restriction of memory sqlite behaviour, but wanted to check with the list first: 1. Running 2, 3, ... 6 multi threaded readers of a single *memory *sqlite database (via shared cache mode) on an 8 core cpu shows no throughput gain at all compared to single threaded throughput. In fact, it shows a throughput drop: i.e. if a single thread can do N simple queries/sec, 2 threads .. up to 6 threads do a little less (10% drop) in total. This suggests that access to memory sqlite can only be serialized? 2. Running the same example on sqlite *file *(multi threaded mode; WAL journal) scales almost linearly; so 6 threads provide nearly 6xN throughput. Single threaded throughput is a bit slower (around 15-20%) than single threaded in-memory access (expected). So, memory sqlite is not really usable with multiple threads (readers). While one might expect that multiple readers of *memory *content could scale even better than with file content. Can this restriction be lifted? Is there some special mode possible to achieve scaling up throughput with multiple threads for memory sqlite content? Thanks _______________________________________________ sqlite-users mailing list [email protected] http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
