现象

最近工作中给公司的系统中增加了一些网络有关的功能，它是基于GatewayWorker的，启动后报告类似如下的错误信息：
Cannot find module (IP-MIB): At line 0 in (none)
Cannot find module (IF-MIB): At line 0 in (none)
Cannot find module (TCP-MIB): At line 0 in (none)
Cannot find module (UDP-MIB): At line 0 in (none)
Cannot find module (HOST-RESOURCES-MIB): At line 0 in (none)
Cannot find module (SNMPv2-MIB): At line 0 in (none)
Cannot find module (SNMPv2-SMI): At line 0 in (none)
Cannot find module (NOTIFICATION-LOG-MIB): At line 0 in (none)
Cannot find module (UCD-SNMP-MIB): At line 0 in (none)
Cannot find module (UCD-DEMO-MIB): At line 0 in (none)
Cannot find module (SNMP-TARGET-MIB): At line 0 in (none)
Cannot find module (NET-SNMP-AGENT-MIB): At line 0 in (none)
Cannot find module (SNMP-VIEW-BASED-ACM-MIB): At line 0 in (none)
Cannot find module (SNMP-COMMUNITY-MIB): At line 0 in (none)
Cannot find module (NET-SNMP-EXTEND-MIB): At line 0 in (none)
Cannot find module (UCD-DLMOD-MIB): At line 0 in (none)
Cannot find module (SNMP-FRAMEWORK-MIB): At line 0 in (none)
Cannot find module (SNMP-MPD-MIB): At line 0 in (none)
Cannot find module (SNMP-USER-BASED-SM-MIB): At line 0 in (none)
Cannot find module (SNMP-NOTIFICATION-MIB): At line 0 in (none)
Cannot find module (SNMPv2-TM): At line 0 in (none)

原因

根据错误信息和网上找到的资料，说是没有开启php_snmp.dll这个扩展，但是查看PHP.ini，发现该扩展其实是打开的，进一步深入分析，确认应该是本机没有安装net-SNMP。

解决

到net-SNMP下载一个安装包，注意只有32位的，不过64位机器上也可以用。运行该安装包使用默认路径安装完毕后，确认PHP.ini中开启了php_snmp.dll，重新启动GatewayWorker，问题解决。