I use hibernate+mysql in my application, and tomcat4 as webserver.
I found that when tomcat has been running over 12 hours, access to
database will be unavailable, and a "java.net.SocketException: Connection reset" is thrown.
I wonder if I should define timeout property in my hibernate.cfg.xml, but in fact I even don't know whether this property
exists

which pool are you using, i think it iq your db that is disconnecting not hibernate...

I think I use a default pool, following is part of my hibernate.cfg.xml

<property name="hibernate.connection.driver_class">org.gjt.mm.mysql.Driver</property>
<property name="hibernate.connection.username">jazz</property>
<property name="hibernate.connection.password">doit</property>
<property name="hibernate.connection.pool.size">1</property>
<property name="hibernate.dialect">net.sf.hibernate.dialect.MySQLDialect</property>
<property name="statement_cache.size">25</property>
<property name="jdbc.fetch_size">50</property>
<property name="jdbc.batch_size">30</property>
<property name="show_sql">false</property>

try proxool with connection check every hour for example

Is it possible that mysql close the connection after several hours' idle?
For I leave the tomcat open when off duty, and find access is not available
the next morning

everything is possible ;)

what is proxool? and would you provide the code to check the connection? I'm really a greenhand to hibernate

read the reference guide, proxool is a connection pool, and checking the connection is done by the pool if you configure it well

MySQL is well known to terminate idle connections after 8 hours by default, although you can increase this to a few days in the my.cnf file. From my experience both C3P0 and DBCP are vulnerable to MySQL's drops. I've heard Proxool is a better choice, but I've also heard that Hibernate doesn't read the relevant recheck settings from its configuration file. Does anyone have a working solution to this problem?

http://www.hibernate.org/hib_docs/api/n ... nment.html

static String C3P0_ACQUIRE_INCREMENT
Number of connections acquired when pool is exhausted
static String C3P0_IDLE_TEST_PERIOD
Idle time before a C3P0 pooled connection is validated
static String C3P0_MAX_SIZE
Maximum size of C3P0 connection pool
static String C3P0_MAX_STATEMENTS
Maximum size of C3P0 statement cache
static String C3P0_MIN_SIZE
Minimum size of C3P0 connection pool
static String C3P0_TIMEOUT
Maximum idle time for C3P0 connection pool
static String C3P0_VALIDATE_CONNECTION
Deprecated. use C3P0_IDLE_TEST_PERIOD


check string values for hibernate.cfg.xml

for proxool you need to specify a configuration file

I'll try it - thanks Anthony!

Scott

FYI :

DBCP (jakarta) is another connection pool for tomcat with reconnect feature for mysql
very easy in setup !

DBCP is also bugged... be carefull!