MySQL Socket refuses connection after thousands of successive connections

I am currently trying to populate a MySQL5.1 database on a current Ubuntu machine with >5,000,000 entries. Due to the program's architecture, for each INSERT statement a new database connection is opened and closed. I am aware that this is an expensive operation to do, but changing this would require to change a loooot of code, so I'd rather avoid that.

The problem I am facing is that after a while (usually about 12 seconds, but this number increases after some retries) this process is not able to connect to the database any more. Other processes can connect to the database without any problem.

I do not think that this is an MySQL issue, cause none of the MySQL logs report any errors. Also, there is max 1 connection open at a time (which I checked by taking a look at the MySQL status variables).

Question: Is there a limit of how many successive connections to the socket can be opened in a given time frame?

Here is a simplified perl-script (the actual program is in Java) that leads to the same problem (the database-variables are not included):

# ...
my $i = 0;
my $DBH = 0;
for ($i = 0;$i &开发者_如何学编程lt; $MAX; ++$i) {
  $DBH = DBI->connect("DBI:mysql:$DBNAME:$DBHOST:$DBPORT", $DBUSER, $DBPW)
    or die ("Error - Connection to database failed: \n   $i times ok\n".DBI->errstr);

  $DBH -> disconnect;
  if ($i % 10000 == 0) {
    print $i. " ";
  }
}

Question: Any suggestions/ideas?

try raising the number of allowed connections in /etc/mysql/my.cnf?

max_connections        = 300

if php, change all instances of mysql_connect() to mysql_pconnect() ?

Since you seem to be opening and closing TCP sockets very quickly, you may be accumulating sockets in TIME_WAIT state (see here) and on Linux this could cause a process to run out of file descriptors (whereas on Windows this would likely manifest in all processes on the same box failing to connect rather than just a single process as there are no per process socket limits).

Run netstat on both the client machine that's running the insertion code and the server that houses the db.

If you are accumulating sockets in TIME_WAIT then what you need to do depends on where they are (client or server).