php multiprocess script hangs after enabling grpc extension

[zheco...@gmail.com]

Hi all,

Our application experienced a annoying problem. When enabling grpc.so extension, php script with multiprocess hangs even we don't use any grpc api.

This is reproducible code. I can reproduce it in PHP 5.6 and PHP 7.1. After disable grpc.so extension, it can exit normally.

<?php

    function startWith($str, $prefix) {

        if (strlen($prefix) > strlen($str)) {

            return false;

        }

        return substr($str, 0, strlen($prefix)) === $prefix;

    }

    /**

     * @param     $daemonName    string

     * @param     $callback      callback 

     * @param     $processAmount int

     * @param     $timeOut       if it's not zero, child process will exit after $timeOut seconds

     */

    function restartDaemons($daemonName, $callback, $processAmount = 1, $timeOut = 0)

    {

        $daemonName = strtolower($daemonName);

        // control child processes via file existence

        $pidDir = RUNTIME_PATH . DIRECTORY_SEPARATOR . 'pid';

        if (!is_dir($pidDir)) {

            mkdir($pidDir, 0777, true);

        }

        //clear pid files

        $pidDirHandle = opendir($pidDir);

        while ($fileName = readdir($pidDirHandle)) {

            if (startWith($fileName, $daemonName . '.worker.')) {

                @unlink($pidDir . DIRECTORY_SEPARATOR . $fileName);

                echo 'CLEAN_PID_FILE' . "\n";

            }

        }

        for ($i = 0; $i < $processAmount; $i++) {

            $pid = pcntl_fork();

            if ($pid == 0) {

                //child processe logic

                $pid     = getmypid();

                $pidFile = $pidDir . DIRECTORY_SEPARATOR . $daemonName . '.worker.' . $pid;

                touch($pidFile);

                echo "worker start: " . ($i + 1) . "/$processAmount" . PHP_EOL;

                $startDaemonTime[$i] = microtime(true);

                while (file_exists($pidFile)) {

                    if($timeOut > 0 && microtime(true) - $startDaemonTime[$i]  > $timeOut){

                        break;

                    }

                    $roundStartTime = microtime(true);

                    $runSuccess     = $callback($processAmount, $i);

                    if (!$runSuccess) {

                        sleep(1);

                    } else {

                    }

                }

                echo "worker exit: " . ($i + 1) . "/$processAmount" . PHP_EOL;

                exit(0);

            }

        }

        //parent process waits for child processes

        for ($i = 0; $i < $processAmount; $i++) {

            $spId = pcntl_wait($status);

            if ($status != 0) {

            }

        }

    }

restartDaemons('haha', function() {return true;}, 10, 10);

I use strace to see what's last system call, this is output

[root@c3d1d6a011ac /]# strace -p 209

Process 209 attached

futex(0x7fe261ffb764, FUTEX_WAIT_PRIVATE, 1, NULL

Please help me. Guide me to some debug approaches or something.

Thanks.

[zheco...@gmail.com]

Solved. See https://github.com/grpc/grpc/issues/13412

在 2019年7月15日星期一 UTC+8下午12:16:05，zheco...@gmail.com写道：