Le 18/09/2013 16:50, Oleg Kalnichevski a écrit :
On Wed, 2013-09-18 at 16:33 +0200, Boris Granveaud wrote:
...
I'm not very comfortable with this solution because of these thread
synchronization issues. I also have to do the same on idle connections
and each enumeration, even if it is fast, locks the pool. It is a pity
that it is not possible to alter the behavior of
PoolingHttpClientConnectionManager.releaseConnection.
Here is my complete code if you see what's wrong:
There is probably nothing wrong with your code. If you intend to shut
down connections 'midair' so to speak, this is what you have to live
with. Changing #releaseConnection will not help given that time to live
and expiry attributes apply to idle connections only.
As far as I understand, #releaseConnection resets the connection expiry
date with the keepalive value because the connection has just been used.
So if I was able to remove this behavior, the connection will "expire"
for example 60 seconds after its creation even if it is intensively used.
Or I could let the keepalive and expiry management, and add something
like this:
public void releaseConnection(
(...)
if (conn.isOpen()) {
entry.setState(state);
entry.updateExpiry(keepalive, tunit != null ? tunit
: TimeUnit.MILLISECONDS);
if (System.currentTimeMillis() - entry.getCreated()
> maxAge) {
entry.closeConnection();
}
}
Maybe would it be interesting to make this maxAge parameter standard in
PoolingHttpClientConnectionManager. What do you think?
Boris.
Connection manager's job is to keep track of available persistent
connections and enforce certain time-to-live constraints for those
connections. It is not meant to police busy connections leased by worker
threads.
Nothing prevents you from creating a custom connection manager, though,
tailored specifically to your application needs.
My intention is not to close busy connections but to enforce a maxAge
policy when the connection is released to the pool. I see this as
complementary to keepalive.
Sure I could extend PoolingHttpClientConnectionManager but this implies
some code duplication (at least releaseConnection) and reflection to
access CPoolEntry.
My point is that it is difficult to add this feature externally, but it
could be easily integrated as a standard behavior as does Tomcat JDBC
Pool for example (see maxAge parameter
http://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html#Tomcat_JDBC_Enhanced_Attributes).
Boris.
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