Alex,
On 3/12/21 16:32, My Subs wrote:
---- On Fri, 12 Mar 2021 02:35:27 -0500 Mark Thomas <ma...@apache.org> wrote
----
> On 12/03/2021 03:57, My Subs wrote:
> > Hello,
> >
> > I'm using Tomcat 10.0.0. Suppose I call setAutoCommit(false) on a
connection obtained from a Tomcat JDBC Connection Pool. Then I do some stuff with
the connection, call commit() or rollback() and finally call close() on it without
ever calling setAutocommit(true).
> >
> > What will the autocommit state of that connection be, the next time the
pool gives it to my code? Will it be in the same state I left it, that is, with
autocommit set to false, or will it be reverted back to the default state (autocommit
set to true)?
>
> The simplest way to be sure is to run a test with a pool size of 1.
>
> A quick look at the code (I might have missed something) suggests that
> if defaultAutoCommit is configured then it will be reset to that default
> value. Otherwise it will be unchanged from when the connection was
> returned to the pool.
>
> Mark
>
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Hi Mark,
Thanks for your comment. I found this on
https://tomcat.apache.org/tomcat-10.0-doc/jdbc-pool.html:
"The only state the pool itself inserts are defaultAutoCommit, defaultReadOnly,
defaultTransactionIsolation, defaultCatalog if these are set. These 4 properties are only
set upon connection creation. Should these properties be modified during the usage of the
connection, the pool itself will not reset them."
It seems to say that connections will not be reverted back to the default
auto-commit state even if defaultAutoCommit is set. Given your reading of the
source code, might it be that the docs are wrong?
I think the docs can easily be misunderstood.
I don't use the tomcat-pool but I do use the *other* pool provided by
Tomcat and they are generally expected to be (mostly) interchangeable.
A connection pool which doesn't reset the auto-commit state on
connection-return operation would IMO be considered very badly broken.
tomcat-pool allows you to NOT specify a default in which case
Connection.setAutoCommit() will never be called *at all* by the pool.
That seems like reasonable behavior (don't mess with my stuff!), but it
means that the application will *always* have to reset the auto-commit
state to a known value *every single time* a connection is borrowed.
Since the whole point of the pool is to manage this kind of thing, I
would argue that having defaultAutoCommit NOT set to anything would be
considered very bad practice.
If you set defaultAutoCommit="true", you should expect that, when your
connections are returned to the pool, that setAutoCommit(true) will be
called every single time the connection is returned to the pool --
usually by the application calling Connection.close().
Are you worried about a particular use-case or are you just being
extra-vigilant? Or are you observing some unexpected behavior?
-chris
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