为什么在使用multi_curl同时调用多个php脚本时脚本执行有延迟？

Question

我有一个脚本，可以同时调用大约40个单独的php脚本（位于同一台服务器上）。我注意到每个单独的php脚本的启动延迟了5秒钟。服务器负载的CPU和内存似乎很好，不交换，看上面的命令下来：

top - 22:32:36 up 1:06, 1 user, load average: 0.18, 0.05, 0.01 
Tasks: 181 total, 1 running, 179 sleeping, 0 stopped, 1 zombie 
Cpu(s): 0.0%us, 0.5%sy, 0.0%ni, 99.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st 
Mem: 1048576k total, 1024144k used, 24432k free, 20160k buffers 
Swap: 2097144k total,  0k used, 2097144k free, 352520k cached 

在结合了multi_curl所有请求循环的最后脚本通常具有最大的延迟。我在每个剧本的开头测量了延迟。

我能做些什么来防止这种延迟？

下面是我的httpd.conf

# 
# This is the main Apache HTTP server configuration file. It contains the 
# configuration directives that give the server its instructions. 
# See <URL:http://httpd.apache.org/docs/2.2> for detailed information. 
# In particular, see 
# <URL:http://httpd.apache.org/docs/2.2/mod/directives.html> 
# for a discussion of each configuration directive. 
# 
# Do NOT simply read the instructions in here without understanding 
# what they do. They're here only as hints or reminders. If you are unsure 
# consult the online docs. You have been warned. 

ServerRoot "/etc/httpd" 
Listen 80 

#LoadModule dummy_module /usr/lib/apache/mod_dummy.so 
#LoadModule php5_module  /usr/lib/apache/libphp5.so 
Include /etc/httpd/conf/extra/httpd-phpmodules.conf 

User apache 
Group apache 

KeepAlive On 
KeepAliveTimeout 30 

ServerAdmin admin@localhost 
DocumentRoot "/var/www/html" 

MaxClients 800 
MaxRequestsPerChild 800 

<Directory /home/*> 
    AllowOverride All 
    Options -MultiViews -Indexes FollowSymlinks IncludesNoExec +Includes 
<Limit GET POST OPTIONS PROPFIND> 
    Order allow,deny 
    Allow from all 
</Limit> 
<LimitExcept GET POST OPTIONS PROPFIND> 
    Order deny,allow 
    Deny from all 
</LimitExcept> 
</Directory> 

<Directory /> 
    Options All 
    AllowOverride All 
</Directory> 

<Directory "/var/www/html"> 
    Options Indexes FollowSymLinks 
    AllowOverride All 
    Order allow,deny 
    Allow from all 
    <IfModule mod_suphp.c> 
     suPHP_Engine On 
     suPHP_UserGroup webapps webapps 
    SetEnv PHP_INI_SCAN_DIR 
    </IfModule> 
</Directory> 

<IfModule mod_dir.c> 
    DirectoryIndex index.html index.htm index.shtml index.php index.php5 index.php4 index.php3 index.phtml index.cgi 
</IfModule> 

<FilesMatch "^\.ht"> 
    Order allow,deny 
    Deny from all 
    Satisfy All 
</FilesMatch> 

ErrorLog /var/log/httpd/error_log 
LogLevel warn 

#replace %b with %O for more accurate logging 
<IfModule mod_logio.c> 
    LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined 
    LogFormat "%h %l %u %t \"%r\" %>s %O" common 
    LogFormat "%O %I" bytes 
    LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio 
</IfModule> 

    CustomLog /var/log/httpd/access_log common 

<IfModule mod_alias.c> 
    # Include some DirectAdmin alias 
    Include conf/extra/httpd-alias.conf 
</IfModule> 

<Directory "/var/www/cgi-bin"> 
    AllowOverride None 
    Options None 
    Order allow,deny 
    Allow from all 
</Directory> 

DefaultType text/plain 

<IfModule mod_mime.c> 
    TypesConfig conf/mime.types 
    AddType application/x-gzip .tgz 
    AddEncoding x-compress .Z 
    AddEncoding x-gzip .gz .tgz 
    AddType application/x-compress .Z 
    AddType application/x-gzip .gz .tgz 
    AddHandler cgi-script .cgi 
    AddHandler type-map var 
    AddType text/html .shtml 
    AddOutputFilter INCLUDES .shtml 
    AddType video/x-ms-asf .avi 
    AddType video/mpeg .mpg 
    AddType video/mpeg .mpeg 
    AddType video/quicktime .mov 
    AddType video/x-ms-wmv .wmv 
</IfModule> 

#EnableMMAP off 
#EnableSendfile off 

####################################################################################### 
# Do not change anything in included files, because they are rewritten by DirectAdmin # 
####################################################################################### 

# This is needed for PHP 
Include conf/extra/httpd-php-handlers.conf 

# Server-pool management (MPM specific) 
Include conf/extra/httpd-mpm.conf 

# Multi-language error messages 
Include conf/extra/httpd-multilang-errordoc.conf 

# Fancy directory listings 
Include conf/extra/httpd-autoindex.conf 

# Language settings 
Include conf/extra/httpd-languages.conf 

# User home directories 
#Include conf/extra/httpd-userdir.conf 

# Real-time info on requests and configuration 
Include conf/extra/httpd-info.conf 

# Virtual hosts 
Include conf/extra/httpd-vhosts.conf 

# Local access to the Apache HTTP Server Manual 
#Include conf/extra/httpd-manual.conf 

# Distributed authoring and versioning (WebDAV) 
Include conf/extra/httpd-dav.conf 

# Various default settings 
Include conf/extra/httpd-default.conf 

# Secure (SSL/TLS) connections 
Include conf/extra/httpd-ssl.conf 

# Deflate module settings 
Include conf/extra/httpd-deflate.conf 

# All the DirectAdmin vhosts 
Include conf/extra/directadmin-vhosts.conf 

# All suPHP directives 
Include conf/extra/httpd-suphp.conf 

# For user configurations not maintained by DirectAdmin. Empty by default. 
Include conf/extra/httpd-includes.conf 

####################################################################################### 
# End of included files that are rewritten by DirectAdmin        # 
####################################################################################### 

<IfModule mod_ssl.c> 
SSLRandomSeed startup builtin 
SSLRandomSeed connect builtin 
</IfModule> 

Answer 1

造成这种情况的最常见的原因是，有些事情是阻止而脚本调用。

这可能是php的构建会话处理程序，即阻止对同一会话id（关键字：竞争条件）的并发请求。如果这是你的问题，你需要一个解决方案，你可以实现你自己的会话处理程序，它以适合你的方式处理会话数据。

另一个原因可能是flock文件或压力过大的系统IO（例如慢速磁盘）。