The mysql has gone away thing:
mysql server timeout:60 (1 min)
I read the source code of SA , and figure out the following
solutions :
sl1 --> set pool_size=1 and max_overflow #this will close all
connections in pool,because the
only conn is closed by my
app with (session.close(),connection.close(),
or result.close()
and all overflow conn are
closed and discarded when recycling to pool
this solution doesn't work)
sl2 --> set pool_recycle = 50 #recycle conn before mysql
timeout 50-60=10 10s for recycle is needed
sl3 --> set poolclass=NullPool #don't use pool strategy
sl4 --> add poollistener
sl5 --> set pool_recycle=1 or 0 # ensure to reclye and create
new conn when check out at any time
after try all these 5 solutions ,the mysql has gone away problem is
still there !!!
I asume the pool has succeffuly recycled the timeout connections ,all
connections we use are new /fresh connection fetched from the
DBAPI,and Exception comes again and again.why???? may be , that is
because our code has used some connection and forget to close them,and
these connecions are not being managed by pool any more (I think
connecions not closed are out of control of pool .I find this in
source code in Connection Class's close method--> then call
_ConnectionFairy . close-->then call fanalizeFairy --> then
pool.return_conn). So we should close all session or resultpoxy object
in our code . And we do this,this time the "mysql has gone away ''
has gone away!!!!
sl6 --> write new pool implementation
sl7 --> rewrite Connection class of SA
These two are difficult and may introduce more problem so I don't use
them. hehehe.
And , one more thing to mention:
Why Connection class in db backend.base alway dispose the underlying
engine and pool whenever there is a DBAPI Error and e.args in
(2006,2000.....)? why on timeout connection will cause all other
connections in pool being closed ??
why not try one more times to finish the work before raise this
exception??
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