iOS-FMDB使用和内存

Question

I have been tracking down memory leaks in my iOS app and I keep coming back to the following code using the leaks instrument:

NSMutableArray *resultSet = [[NSMutableArray alloc] initWithCapacity:3];

NSAutoreleasePool *innerPool = [[NSAutoreleasePool alloc] init];

FMResultSet *rs = [db executeQuery:query,equipmentID];
while ([rs next])
{
    [resultSet addObject: [rs resultDict]];
}
[rs close];
[innerPool release];

return [resultSet autorelease];

Is this the correct (in terms of memory management) usage of FMDB? Here is a screenshot of the leaks instrument:

leaks

Detailed Screenshot of the leak:

detail

Answer 1

Yes, this is correct memory management. The [rs close]; line is technically unnecessary, because it will happen (if it hasn't already) when the FMResultSet is deallocated (as part of the pool draining). But putting it in there explicitly is fine.

Is it possible you're over-retaining the return array?

Answer 2

SQLite allocates and keeps a bunch of memory, which is only freed when the database is closed. You can also adjust how much memory it will allocate by issuing a 'pragma cache_size = nnn' command.

See this related question and answer:

memory leak (?) after sqlite+fmdb vacuum command