java mail: set

最新推荐文章于 2022-12-16 17:57:52 发布

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#java #javamail #properties #application #socket #search

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本文记录了一次生产环境中邮件发送线程挂起的问题排查过程。问题表现为多个邮件发送线程在Socket读取阶段阻塞。通过互联网搜索并调整JavaMail的SMTP超时设置，最终解决了此问题。

Problem: email thread is hanging at socket read

Today we found a email problem in production, all of the mail threads (3 threads) are hanging/sitting/blocking at same point

at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.io.BufferedInputStream.fill(BufferedInputStream.java:218) at java.io.BufferedInputStream.read(BufferedInputStream.java:237) - locked <0x9698d6c0> (a java.io.BufferedInputStream) at com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:56) at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:757) at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:673) at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:168) at javax.mail.Service.connect(Service.java:227) at javax.mail.Service.connect(Service.java:131) at javax.mail.Service.connect(Service.java:87) at com.sun.mail.smtp.SMTPTransport.connect(SMTPTransport.java:105) - locked <0x9698d6e0> (a com.sun.mail.smtp.SMTPTransport) at javax.mail.Transport.send0(Transport.java:162) at javax.mail.Transport.send(Transport.java:80)

I search the "javax.mail.Transport.send" and "com.sun.mail.smtp.SMTPTransport.readServerResponse", got no hits.

while my colleague get answer from internet.

http://jira.sakaiproject.org/browse/KNL-96

http://forums.sun.com/thread.jspa?forumID=43&threadID=474662

"I have a servlet which uses JavaMail to send out emails to a smtp server. During our peak access hours, we have many requests to send out emails, after a while my application went into CLOSE WAIT accumulation and finally my application server stops processing."

"ExecuteThread: '11' for queue: 'default'" daemon prio=5 tid=0x39fb28 nid=0x18 runnable [0xbf980000..0xbf981a38] at java.net.SocketInputStream.socketRead(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:85) at java.io.BufferedInputStream.fill(BufferedInputStream.java:181) at java.io.BufferedInputStream.read(BufferedInputStream.java:199) at com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:56) at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:929) at com.sun.mail.smtp.SMTPTransport.issueCommand(SMTPTransport.java:878) at com.sun.mail.smtp.SMTPTransport.finishData(SMTPTransport.java:820) at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:322) at javax.mail.Transport.send0(Transport.java:164) at javax.mail.Transport.send(Transport.java:81)

Solution

"JavaMail send() method is synchronous call. If the smtp server does not return a response JavaMail may wait forever.

Therefore you should set the smtp timeout properties:
mail.smtp.connectiontimeout
mail.smtp.timeout"

Properties props = new Properties(); props.put("mail.smtp.host", hostid); props.put("mail.smtp.port", smtpPort); props.put("mail.smtp.connectiontimeout","600000");//timeout 10 mins props.put("mail.smtp.timeout","600000");//timeout 10 mins mysession = Session.getDefaultInstance(props);

My postmortem

1. try different search keywords in problem description : blocking, handing, never return. setting...

2. try different API:"javax.mail.Transport.send

"javax.mail.Transport.send" is abstract API.

"com.sun.mail.smtp.SMTPTransport.readServerResponse" is bottom.

Try a middle point: com.sun.mail.smtp.SMTPTransport.connect

3.We do not get the root cause: why 'CLOSE_WAIT ' accumulation.

It means one peer of socket connection is closed, while the other do not.