PHP comet usleep blocking apache mpm?

问题

I've a comet there I run an while loop in this way

$items = $statement->fetchAll();//statement is a PDO Statement
$iteration = 0;
while(count($items) == 0 && $iteration < 100){
    $items = $statement->fetchAll();
    usleep(10000);
    ++$iteration;
}

When the comet runs I can see all other HTTP requests are pending. even non-database requests are pending. Why ?

回答1:

You need to manually commit using PDO::commit as the request are being hold in a transaction.

Please see the docs about this behavior:

http://www.php.net/manual/de/pdo.commit.php

http://www.php.net/manual/en/pdo.transactions.php

来源：https://stackoverflow.com/questions/11126465/php-comet-usleep-blocking-apache-mpm