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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