Java log4j错误邮件挂起线程

我们遇到了一些问题，生产环境对请求的响应非常慢，并且发现Tomcat已经用完了工作线程。这在一定程度上是由于占用线程的旧特性造成的，但我们也发现了一些关于log4j和邮件错误日志的有趣内容。有一个log4j错误日志线程试图发送一封邮件，阻止了34个其他线程。来自阻塞线程的线程转储如下所示：

"http-apr-80-exec-777" - Thread t@4195
   java.lang.Thread.State: RUNNABLE
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.read(SocketInputStream.java:150)
    at java.net.SocketInputStream.read(SocketInputStream.java:121)
    at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:97)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:265)
    - locked <45b6408b> (a java.io.BufferedInputStream)
    at com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:75)
    at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:1440)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1260)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:370)
    at javax.mail.Service.connect(Service.java:275)
    at javax.mail.Service.connect(Service.java:156)
    at javax.mail.Service.connect(Service.java:105)
    at javax.mail.Transport.send0(Transport.java:168)
    at javax.mail.Transport.send(Transport.java:98)
    at org.apache.log4j.net.SMTPAppender.sendBuffer(SMTPAppender.java:416)
    at org.apache.log4j.net.SMTPAppender.append(SMTPAppender.java:256)
    at org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:251)
    - locked <54ebd98f> (a org.apache.log4j.net.SMTPAppender)
    at org.apache.log4j.helpers.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:66)
    at org.apache.log4j.Category.callAppenders(Category.java:206)
    - locked <731a1e23> (a org.apache.log4j.spi.RootLogger)
    at org.apache.log4j.Category.forcedLog(Category.java:391)
    at org.apache.log4j.Category.error(Category.java:305)
    at org.apache.jsp.errorpage_jsp._jspService(errorpage_jsp.java:197)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:489)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
    at org.apache.catalina.core.StandardHostValve.custom(StandardHostValve.java:467)
    at org.apache.catalina.core.StandardHostValve.throwable(StandardHostValve.java:412)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:201)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
    - locked <6af9560> (a org.apache.tomcat.util.net.SocketWrapper)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - locked <7a82445e> (a java.util.concurrent.ThreadPoolExecutor$Worker)

"http-apr-80-exec-787" - Thread t@4306
   java.lang.Thread.State: BLOCKED
    at org.apache.log4j.Category.callAppenders(Category.java:204)
    - waiting to lock <731a1e23> (a org.apache.log4j.spi.RootLogger) owned by "http-apr-80-exec-777" t@4195
    at org.apache.log4j.Category.forcedLog(Category.java:391)
    at org.apache.log4j.Category.error(Category.java:305)
    at org.apache.jsp.errorpage_jsp._jspService(errorpage_jsp.java:197)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:489)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
    at org.apache.catalina.core.StandardHostValve.custom(StandardHostValve.java:467)
    at org.apache.catalina.core.StandardHostValve.throwable(StandardHostValve.java:412)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:201)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
    - locked <2d079e0c> (a org.apache.tomcat.util.net.SocketWrapper)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - locked <7dac19bb> (a java.util.concurrent.ThreadPoolExecutor$Worker)

“http-apr-80-exec-777”-线程t@4195
java.lang.Thread.State:可运行
位于java.net.SocketInputStream.socketRead0（本机方法）
位于java.net.SocketInputStream.read（SocketInputStream.java:150）
位于java.net.SocketInputStream.read（SocketInputStream.java:121）
位于com.sun.mail.util.TraceInputStream.read（TraceInputStream.java:97）
在java.io.BufferedInputStream.fill处（BufferedInputStream.java:246）
在java.io.BufferedInputStream.read处（BufferedInputStream.java:265）
-锁定（java.io.BufferedInputStream）
位于com.sun.mail.util.LineInputStream.readLine（LineInputStream.java:75）
在com.sun.mail.smtp.SMTPTransport.readServerResponse（SMTPTransport.java:1440）上
在com.sun.mail.smtp.SMTPTransport.openServer上（SMTPTransport.java:1260）
在com.sun.mail.smtp.SMTPTransport.protocolConnect（SMTPTransport.java:370）上
在javax.mail.Service.connect（Service.java:275）
在javax.mail.Service.connect（Service.java:156）
在javax.mail.Service.connect（Service.java:105）
位于javax.mail.Transport.send0（Transport.java:168）
在javax.mail.Transport.send（Transport.java:98）
位于org.apache.log4j.net.SMTPAppender.sendBuffer（SMTPAppender.java:416）
位于org.apache.log4j.net.SMTPAppender.append（SMTPAppender.java:256）
位于org.apache.log4j.AppenderSkeleton.doAppend（AppenderSkeleton.java:251）
-锁定（org.apache.log4j.net.SMTPAppender）
位于org.apache.log4j.helpers.appenderatachableimpl.appenderlooponappenders（appenderatachableimpl.java:66）
位于org.apache.log4j.Category.callAppenders（Category.java:206）
-锁定（org.apache.log4j.spi.RootLogger）
位于org.apache.log4j.Category.forcedLog（Category.java:391）
位于org.apache.log4j.Category.error（Category.java:305）
在org.apache.jsp.errorpage\u jsp.\u jsp服务上（errorpage\u jsp.java:197）
位于org.apache.jasper.runtime.HttpJspBase.service（HttpJspBase.java:70）
位于javax.servlet.http.HttpServlet.service（HttpServlet.java:728）
位于org.apache.jasper.servlet.JspServletWrapper.service（JspServletWrapper.java:432）
位于org.apache.jasper.servlet.JspServlet.serviceJspFile（JspServlet.java:390）
位于org.apache.jasper.servlet.JspServlet.service（JspServlet.java:334）
位于javax.servlet.http.HttpServlet.service（HttpServlet.java:728）
位于org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:305）
位于org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:210）
位于org.apache.catalina.core.ApplicationDispatcher.invoke（ApplicationDispatcher.java:749）
位于org.apache.catalina.core.ApplicationDispatcher.processRequest（ApplicationDispatcher.java:489）
位于org.apache.catalina.core.ApplicationDispatcher.doForward（ApplicationDispatcher.java:412）
位于org.apache.catalina.core.ApplicationDispatcher.forward（ApplicationDispatcher.java:339）
位于org.apache.catalina.core.StandardHostValve.custom（StandardHostValve.java:467）
位于org.apache.catalina.core.StandardHostValve.throwable（StandardHostValve.java:412）
位于org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:201）
位于org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:99）
位于org.apache.catalina.valves.AccessLogValve.invoke（AccessLogValve.java:947）
位于org.apache.catalina.core.StandardEngineValve.invoke（StandardEngineValve.java:118）
位于org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:408）
位于org.apache.coyote.http11.AbstractHttp11Processor.process（AbstractHttp11Processor.java:1009）
位于org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process（AbstractProtocol.java:589）
位于org.apache.tomcat.util.net.aprendop$SocketProcessor.run（aprendop.java:1852）
-锁定（org.apache.tomcat.util.net.SocketWrapper）
位于java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1142）
位于java.util.concurrent.ThreadPoolExecutor$Worker.run（ThreadPoolExecutor.java:617）
运行（Thread.java:745）
锁定可拥有的同步器：
-锁定（java.util.concurrent.ThreadPoolExecutor$Worker）

虽然34个阻塞线程通常如下所示：

"http-apr-80-exec-777" - Thread t@4195
   java.lang.Thread.State: RUNNABLE
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.read(SocketInputStream.java:150)
    at java.net.SocketInputStream.read(SocketInputStream.java:121)
    at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:97)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:265)
    - locked <45b6408b> (a java.io.BufferedInputStream)
    at com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:75)
    at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:1440)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1260)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:370)
    at javax.mail.Service.connect(Service.java:275)
    at javax.mail.Service.connect(Service.java:156)
    at javax.mail.Service.connect(Service.java:105)
    at javax.mail.Transport.send0(Transport.java:168)
    at javax.mail.Transport.send(Transport.java:98)
    at org.apache.log4j.net.SMTPAppender.sendBuffer(SMTPAppender.java:416)
    at org.apache.log4j.net.SMTPAppender.append(SMTPAppender.java:256)
    at org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:251)
    - locked <54ebd98f> (a org.apache.log4j.net.SMTPAppender)
    at org.apache.log4j.helpers.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:66)
    at org.apache.log4j.Category.callAppenders(Category.java:206)
    - locked <731a1e23> (a org.apache.log4j.spi.RootLogger)
    at org.apache.log4j.Category.forcedLog(Category.java:391)
    at org.apache.log4j.Category.error(Category.java:305)
    at org.apache.jsp.errorpage_jsp._jspService(errorpage_jsp.java:197)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:489)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
    at org.apache.catalina.core.StandardHostValve.custom(StandardHostValve.java:467)
    at org.apache.catalina.core.StandardHostValve.throwable(StandardHostValve.java:412)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:201)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
    - locked <6af9560> (a org.apache.tomcat.util.net.SocketWrapper)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - locked <7a82445e> (a java.util.concurrent.ThreadPoolExecutor$Worker)

"http-apr-80-exec-787" - Thread t@4306
   java.lang.Thread.State: BLOCKED
    at org.apache.log4j.Category.callAppenders(Category.java:204)
    - waiting to lock <731a1e23> (a org.apache.log4j.spi.RootLogger) owned by "http-apr-80-exec-777" t@4195
    at org.apache.log4j.Category.forcedLog(Category.java:391)
    at org.apache.log4j.Category.error(Category.java:305)
    at org.apache.jsp.errorpage_jsp._jspService(errorpage_jsp.java:197)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:489)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
    at org.apache.catalina.core.StandardHostValve.custom(StandardHostValve.java:467)
    at org.apache.catalina.core.StandardHostValve.throwable(StandardHostValve.java:412)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:201)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
    - locked <2d079e0c> (a org.apache.tomcat.util.net.SocketWrapper)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
    - locked <7dac19bb> (a java.util.concurrent.ThreadPoolExecutor$Worker)

“http-apr-80-exec-787”-线程t@4306
java.lang.Thread.State:已阻止
位于org.apache.log4j.Category.callAppenders（Category.java:204）
-正在等待“http-apr-80-exec-777”拥有的锁（org.apache.log4j.spi.RootLogger）t@4195
位于org.apache.log4j.Category.forcedLog（Category.java:391）
位于org.apache.log4j.Category.error（Category.java:305）
在org.apache.jsp.errorpage\u jsp.\u jsp服务上（errorpage\u jsp.java:197）
位于org.apache.jasper.runtime.HttpJspBase.service（HttpJspBase.java:70）
位于javax.servlet.http.HttpServlet.service（HttpServlet.java:728）
位于org.apache.jasper.servlet.JspServletWrapper.service（JspServletWrapper.java:432）
位于org.apache.jasper.servlet.JspServlet.serviceJspFile（JspServlet.java:390）
位于org.apache.jasper.servlet.JspServlet.service（JspServlet.java:334）
位于javax.servlet.http.HttpServlet.service（HttpServlet.java:728）
位于org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:305）
位于org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:210）
位于org.apache.catalina.core.ApplicationDispatcher.invoke（ApplicationDispatcher.java:749）
位于org.apache.catalina.core.ApplicationDispatcher.processRequest（ApplicationDispatcher.java:489）
位于org.apache.catalina.core.ApplicationDispa