虚拟机环境，OEL7.2， ORACLE 12.1。 重启主机后，发现监听程序启动好像将近1分钟。
下面是分析过程：
执行监听启动操作，会hang起来一段时间，最终监听启动成功
[oracle@sky-oel7 ~]$ lsnrctl start
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=sky-oel7)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 12.1.0.2.0 - Production
Start Date 12-JAN-2016 16:42:57
Uptime 0 days 0 hr. 0 min. 40 sec
启动耗时40秒。
指定监听的日志等级为16
[oracle@sky-oel7 trace]$ cat /oracle/app/oracle/product/12.1.0/dbhome_1/network/admin/listener.ora
# listener.ora Network Configuration File: /oracle/app/oracle/product/12.1.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = sky-oel7)(PORT = 1521))
)
)
TRACE_LEVEL_LISTENER=16
重新启动监听程序，日志
[oracle@sky-oel7 trace]$ tail -f listener.log
Log messages written to /oracle/app/oracle/diag/tnslsnr/sky-oel7/listener/alert/log.xml
Trace information written to /oracle/app/oracle/diag/tnslsnr/sky-oel7/listener/trace/ora_4179_140717186082304.trc
Trace level is currently 16
Started with pid=4179
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=sky-oel7)(PORT=1521)))
TIMESTAMP * CONNECT DATA [* PROTOCOL INFO] * EVENT [* SID] * RETURN CODE
WARNING: Subscription for node down event still pending
12-JAN-2016 16:10:14 * (CONNECT_DATA=(CID=(PROGRAM=)(HOST=sky-oel7)(USER=oracle))(COMMAND=status)(ARGUMENTS=64)(SERVICE=LISTENER)(VERSION=202375680)) * status * 0
[oracle@sky-oel7 admin]$ vi /oracle/app/oracle/diag/tnslsnr/sky-oel7/listener/trace/ora_4179_140717186082304.trc
2016-01-12 16:09:34.211259 : nttcnp:binding an address to a socket.
2016-01-12 16:09:34.211275 : nttcnp:listening on a bound socket (queue size = 128).
2016-01-12 16:09:34.211324 : nttcnp:getting sockname
2016-01-12 16:09:34.211342 : nttcnp:getting peername
2016-01-12 16:09:34.211355 : nttcnp:exit
2016-01-12 16:09:34.211368 : snlinGetAddrInfo:entry
2016-01-12 16:10:14.256096 : snlinGetAddrInfo:getaddrinfo() failed with error -3
2016-01-12 16:10:14.256193 : snlinGetAddrInfo:exit
2016-01-12 16:10:14.256215 : nttcon:exit
2016-01-12 16:10:14.256241 : nsopen:transport is open
2016-01-12 16:10:14.256261 : nsoptions:entry
没有更多的可用信息。
通过strace进行进程启动信息分析
[oracle@sky-oel7 ~]$ strace -f -t -o ~/listener.trc lsnrctl start
查看strace日志信息
5042 16:42:57 socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK, IPPROTO_IP) = 13
5042 16:42:57 connect(13, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("172.24.97.1")}, 16) = 0
5042 16:42:57 poll([{fd=13, events=POLLOUT}], 1, 0) = 1 ([{fd=13, revents=POLLOUT}])
5042 16:42:57 sendto(13, ":\26\1\0\0\1\0\0\0\0\0\0\10sky-oel7\tworkgroup\0"..., 36, MSG_NOSIGNAL, NULL, 0) = 36
5042 16:42:57 poll([{fd=13, events=POLLIN}], 1, 5000) = 0 (Timeout)
5042 16:43:02 socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK, IPPROTO_IP) = 14
5042 16:43:02 connect(14, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.191.1")}, 16) = 0
5042 16:43:02 poll([{fd=14, events=POLLOUT}], 1, 0) = 1 ([{fd=14, revents=POLLOUT}])
5042 16:43:02 sendto(14, ":\26\1\0\0\1\0\0\0\0\0\0\10sky-oel7\tworkgroup\0"..., 36, MSG_NOSIGNAL, NULL, 0) = 36
5042 16:43:02 poll([{fd=14, events=POLLIN}], 1, 5000) = 0 (Timeout)
上面的信息看出，是由于地址解析失败造成网络超时。
这些地址都是安装时，自动产生的DNS地址信息，由于环境发生变化,DNS地址不同，造成访问操作
[root@sky-oel7 ~]# cat /etc/resolv.conf
# Generated by NetworkManager
search workgroup
nameserver 172.24.97.1
nameserver 192.168.191.1
屏蔽这些地址后，listener启动正常。
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