Martin Dyulgerov wrote:
Hello again group!
Phil: I followed your advice and remove some of the configuration
lines for my pool, here is the configuration i use at the moment:
GenericObjectPool.Config config=new GenericObjectPool.Config();
config.maxActive=15;
config.maxWait=1000;
config.testOnBorrow=true;
and still i get the following error:
"Exception: Cannot get a connection, pool error Timeout waiting for
idle object SQL Exception Connection is closed. SQLException
Connection is closed."
MySQL shows that there are active 19 connections (19 rows in set (0.00
sec)) as a result of "mysql> SHOW FULL PROCESSLIST\G; "... When i
begin to work on my application (about 3 hours earlier today), there
were only 6 connections, and then, at some point they increment to
that number (i am more than sure that no one is using the application
besides me, and all the connections use the same database as my
application - so they have to belong to it, to the pool) My
application is running for about 7 hours to this moment after i made
the changes and restarted it. Can you please help me with some
suggestions onconfiguring the pool wright... I am getting pretty
desperate by now :( Thanks in advance!
Looks like you may not be closing your connections on all control
paths. Are you sure there are not exception conditions that could cause
your close() activations to be missed?
Martin
Phil Steitz wrote:
Martin Dyulgerov wrote:
Hello group!
This is the first time i actuali write something in here. First of
all - please excuse my bad english, it is not my native language.
Now to get to the point... I have problems implementing DBCP on my
Tomcat 6.0.18 in my web applications. I don't want to use JNDI, that
is why i have ServletContextListener, in witch i do as follows in
order:
1.Define GenericObject Pool
2. Define ConnectionFactory as implementation of
DriverManagerConnectionFactory
3.Define PoolableConnectionFactory with the previously created
GenericObjectPool and ConnectionFactory
4.Define PoolingDataSource with the GenericObjectPool object from
step 1
Then i "stick" my PoolingDataSource to the servlet context, retreive
it in my JSPs and servlets and aquire a connection via
"getConnection()" (which returns Connection object). I make sure to
close() all my connections at the edn of the pages...I am sure that
the connections that are opened dont exceed the number 100 (which is
the maximum number of connections on my database - a MySQL database
system), so i think there must be something wrong with my pooling
code. The exact error i get is:
"Exception: Cannot get a connection, pool error Timeout waiting for
idle object SQL Exception Connection is closed. SQLException
Connection is closed." At some point i began to ask myself if it the
problem is caused by the restarts(reloads) i do for that exact
application, because the other work fine (byt i dont play with them
that much)... My configurations for the GenericObjectPool and
DriverManagerConnectionFactory are as follows:
GenericObjectPool.Config config=new GenericObjectPool.Config();
config.maxActive=15;
config.maxIdle=10;
config.minIdle=5;
config.maxWait=3000;
config.testOnBorrow=true;
config.testOnReturn=true;
config.testWhileIdle=true;
config.timeBetweenEvictionRunsMillis=1000;
config.minEvictableIdleTimeMillis=1000;
Properties p=new Properties();
p.setProperty("user", user);
p.setProperty("password", password);
p.setProperty("useUnicode", "true");
p.setProperty("characterEncoding", "CP1251");
p.setProperty("autoReconnect", "true");
Can You help me please? Any help will be appriciated. Thanks in
advance, and accept my apologies if i have breaked some rules of the
group or something like that.
These settings make it hard for the pool to manage connections:
config.maxIdle=10;
config.minIdle=5;
config.timeBetweenEvictionRunsMillis=1000;
config.minEvictableIdleTimeMillis=1000;
The first two force the pool to try to keep the number of idle
connections between 5 and 10, which is going to force it to close /
open frequently to stay within that relatively narrow range. Unless
you really need both of these, I would recommend eliminating one or
both of them.
The second two are probably the source of your problem. These
parameters are specified in milliseconds (thousandths of a second).
The first one tells the pool to kick off an evictor run every second
and the second tells it to destroy any connections that sit idle for
more than a second. This will create lots of connection churn and
also pool access contention as the idle object evictor runs every
second and closes connections that have been idle and then tries to
create new ones to reach minIdle. You should either increase both of
these by at least an order of magnitude or drop them. Unless you
really want to close connections that have been idle in the pool for
longer than a specified idle timeout, I would drop these.
Phil
All best,
Martin
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