[soci-users] SQLite lock access errors

[JP]

Hi all,

I'm using a SQLite database, and in my application I have with several
threads reading/writing. Sometimes I get errors accessing the database,
probably because one thread tries to read while another is writing. I can
handle this situation using a mutex. However, there is also an external
application that works with the same database, and I can not synchronize
the access in any way between that application and mine. What surprises me
is that I thought SQLite had a kind of time-out, around 5 seconds, before
aborting the operation, if there are access problems, but the SOCI methods
abort the operation instantly, isn't there any time-out? or re-try the
operation a number of times?

Thanks a lot in advance.
JP

[Felix Krause]

Post by JP
Hi all,
I'm using a SQLite database, and in my application I have with several
threads reading/writing. Sometimes I get errors accessing the database,
probably because one thread tries to read while another is writing. I can
handle this situation using a mutex. However, there is also an external
application that works with the same database, and I can not synchronize
the access in any way between that application and mine. What surprises me
is that I thought SQLite had a kind of time-out, around 5 seconds, before
aborting the operation, if there are access problems, but the SOCI methods
abort the operation instantly, isn't there any time-out? or re-try the
operation a number of times?

You can set the timeout like this (assuming sql is a soci::session):

soci::sqlite3_session_backend * sessionBackEnd =
static_cast<soci::sqlite3_session_backend *>(sql.get_backend());
sqlite_api::sqlite3_busy_timeout(sessionBackEnd->conn_, 1000);

This will set the timeout to 1 second for your session.

Regards,
Felix

[JP]

Hi Felix,

I've seen that, actually, a time-out of 1 secs. is already set in the
backend of SQLite, within th source.cpp. But, this is very strange, because
that this time-out is not used at all when I get the errors; I'd say that
the time-out is zero, when there is another process reading the database,
and I try to make an "insert" query, the SOCI throws an exception without
any time-out...

Thanks.
JP

Post by Felix Krause

Post by JP
Hi all,
I'm using a SQLite database, and in my application I have with several
threads reading/writing. Sometimes I get errors accessing the database,
probably because one thread tries to read while another is writing. I can
handle this situation using a mutex. However, there is also an external
application that works with the same database, and I can not synchronize
the access in any way between that application and mine. What surprises me
is that I thought SQLite had a kind of time-out, around 5 seconds, before
aborting the operation, if there are access problems, but the SOCI methods
abort the operation instantly, isn't there any time-out? or re-try the
operation a number of times?

soci::sqlite3_session_backend * sessionBackEnd =
static_cast<soci::sqlite3_session_backend *>(sql.get_backend());
sqlite_api::sqlite3_busy_timeout(sessionBackEnd->conn_, 1000);
This will set the timeout to 1 second for your session.
Regards,
Felix
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