apsw waiting for another write to finish

[Peng Yu]

Hi,

I have the following python code to write something to a sqlar file.

import apsw
conn = apsw.Connection(sys.argv[1])
c = conn.cursor()
c.execute('''
CREATE TABLE IF NOT EXISTS sqlar(
name TEXT PRIMARY KEY
, mode INT
, mtime INT
, sz INT
, data BLOB)
''')

import zlib
data = sys.stdin.buffer.read()
c.execute('REPLACE INTO sqlar VALUES(?, ?, ?, ?, ?)', [sys.argv[2], 0,
0, len(data), zlib.compress(data)])

But the problem is when multiple processes are trying to write to the
same database file, I got the following error. What is the correct way
to change the code so that it will not raise an exception but write to
the same database when other write operations are finished?

File "xxx.py", line 28, in <module>
c.execute('REPLACE INTO sqlar VALUES(?, ?, ?, ?, ?)',
[sys.argv[2], 0, 0, len(data), zlib.compress(data)])
File "src/cursor.c", line 236, in resetcursor
apsw.BusyError: BusyError: database is locked

--
Regards,
Peng

[Roger Binns]

On 3/9/20 5:25 PM, Peng Yu wrote:
> apsw.BusyError: BusyError: database is locked

https://rogerbinns.github.io/apsw/tips.html#busy-handling

Set a busy timeout to what seems like a reasonably large number to you,
and all should go well.

If you are doing things like leaving transactions open (only one can be
in progress at a time), then good practise is to alter the code to have
the transaction open for less time. 'with' works well:

https://rogerbinns.github.io/apsw/connection.html?highlight=transaction#apsw.Connection.__enter__

Roger

[Peng Yu]

Hi Roger, Thanks. Could you show me the modified code? I am not sure I
can get it completely right. Thanks.

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--
Regards,
Peng