Hi Hick,
You were right I was not finalizing statements and this prevented close
to complete. When I modified my code to finalize all statements before
close it works fine.
However I was always checking return status from sqlite_close_v2 call
and it was always 0. This is fine according to the documentation:
"If sqlite3_close_v2() is called on a database connection
<http://www.sqlite.org/c3ref/sqlite3.html> that still has outstanding
prepared statements <http://www.sqlite.org/c3ref/stmt.html>, BLOB
handles <http://www.sqlite.org/c3ref/blob.html>, and/or sqlite3_backup
<http://www.sqlite.org/c3ref/backup.html> objects then it returns
SQLITE_OK but the deallocation of resources is deferred until all
prepared statements <http://www.sqlite.org/c3ref/stmt.html>, BLOB
handles <http://www.sqlite.org/c3ref/blob.html>, and sqlite3_backup
<http://www.sqlite.org/c3ref/backup.html> objects are also destroyed."
I admit I had missed this sentence, but to be honest, it seems to be
very confusing behaviour.
Regards,
Greg
On 02/07/14 16:22, Hick Gunter wrote:
What is your sequence of calls?
What do you mean by "one connection for the application lifetime" and "others on
demand for each transaction"?
A "connection" is created/destroyed (aka opened/closed) with sqlite3_open resp.
sqlite3_close calls. This opens/closes the underlying file handles.
A "statement" is created/destroyed with sqlite3_prepare resp. sqlite3_finalize
calls. Unfinalized statements will prevent sqlite3_close from working and return an error
code.
My guess is you are not finalizing your statements and not checking
sqlite3_close return status, thus missing SQLite having a lot of open files. Is
there a lsof command or a /proc filesystem or equivalent?
-----Ursprüngliche Nachricht-----
Von: Grzegorz Sikorski [mailto:g.sikor...@kelvatek.com]
Gesendet: Mittwoch, 02. Juli 2014 13:02
An: sqlite-users@sqlite.org
Betreff: [sqlite] Problem with many connections
Hi,
I am not sure if my previous email had reached the list, so I just repeat it:
I am developing sharding database using SQLite3 for embedded application. My code works
fine up to about 1020 connections to the database. After around this number, I get an
error "unable to open database file". I double checked, permissions are OK and
I think I always properly close all connections and never open the same file twice (I
normally keep one connection opened for whole application lifetime and open others on
demand for each transaction). I found this
topic:http://stackoverflow.com/questions/22801987/sqlite3-unable-to-open-database-file-ios
and I am not sure if there is any reason why keeping opened connection in whole
application lifetime is really something I should do? I would prefer to open database
only when it is needed, to avoid risk of file corruption on power loss. Is there any
known issue with multiple open/close operations?
Regards,
Greg
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