[logback-user] Hang with SMTPAppender

[Jeff Jensen]

Using Logback 0.9.24 and SLF4J 1.6.1.

I'm trying to resolve a hang problem with the 
ch.qos.logback.classic.net.SMTPAppender in an integration 
test and using SubethaSMTP as the email server.  We have 
many tests working with SubethaSMTP that send emails, but 
not with Logback, so I know it works for the non-Logback 
configuration.  I've also seen SMTPAppender work in a 
different situation to the production email server.  So I 
think I have a config error somewhere with Logback setup 
to SubethaSMTP, but not sure what, or there is an issue in 
the LB & SS interaction.

This is the SMTPAppender config:

  <appender name="EMAIL" 
class="ch.qos.logback.classic.net.SMTPAppender">
    <layout 
class="ch.qos.logback.classic.html.HTMLLayout">
      
<pattern>%date%contextName%thread%-5level%-55logger{55}%mdc%marker%msg</pattern>
      <throwableRenderer 
class="ch.qos.logback.classic.html.DefaultThrowableRenderer" 
/>
    </layout>
    <SMTPHost>${mail.host.name}</SMTPHost>
    <SMTPPort>${mail.port.number}</SMTPPort>
    <From>${batch.email.address.from}</From>
    <To>${batch.email.address.to.cmrdevelopers}</To>
    <Subject>${batch.email.subject.prefix}Log Email: 
%msg</Subject>
    <evaluator 
class="ch.qos.logback.classic.boolex.OnMarkerEvaluator">
      <marker>EMAIL_DEVS</marker>
    </evaluator>
  </appender>


It hangs on call to SocketInputStream.socketRead0(), which 
is a native method.  Anyone seen/solved this before?

The timeout value is 0 on the socket read (means wait 
forever), so it is  waiting for a response to read.



While I'm trying to resolve this, one thing I'd like to do 
is set the
timeout value so at least it doesn't hang.  I'm not sure 
how to do that with SMTPAppender -
  anyone know how?  The SMTPAppender/SMTPAppenderBase 
 class does not
have a timeout property, but SMTPAppenderBase does pull 
system
properties.  I'm hoping there is a config file-based 
approach to do this
  though...




The following is a call stack captured in the Eclipse 
debugger; the next line-step would go into socketRead0() 
and hang.

    org.eclipse.jdt.internal.junit.runner.RemoteTestRunner 
at localhost:3598   
        Thread [main] (Suspended)   
            SocketInputStream.read(byte[], int, int) line: 
129   
            TraceInputStream.read(byte[], int, int) line: 
97   
            BufferedInputStream.fill() line: 218   
            BufferedInputStream.read() line: 237   
            LineInputStream.readLine() line: 75   
            SMTPTransport.readServerResponse() line: 
1440   
            SMTPTransport.openServer(String, int) line: 
1260   
            SMTPTransport.protocolConnect(String, int, 
String, String) line: 370   
            SMTPTransport(Service).connect(String, int, 
String, String) line: 275   
            SMTPTransport(Service).connect(String, String, 
String) line: 156   
            SMTPTransport(Service).connect() line: 105   
            Transport.send0(Message, Address[]) line: 
168   
            Transport.send(Message) line: 98   
            
SMTPAppender(SMTPAppenderBase<E>).sendBuffer(E) line: 
292   
            SMTPAppender(SMTPAppenderBase<E>).append(E) 
line: 159   
            SMTPAppender(AppenderBase<E>).doAppend(E) 
line: 85   
            
AppenderAttachableImpl<E>.appendLoopOnAppenders(E) line: 
64   
            Logger.appendLoopOnAppenders(ILoggingEvent) 
line: 283   
            Logger.callAppenders(ILoggingEvent) line: 
270   
            Logger.buildLoggingEventAndAppend(String, 
Marker, Level, String, Object[], Throwable) line: 471   
            Logger.filterAndLog_0_Or3Plus(String, Marker, 
Level, String, Object[], Throwable) line: 425   
            Logger.error(Marker, String) line: 592   
            LoggerEmailTest.testEmailSend() line: 99   
            NativeMethodAccessorImpl.invoke0(Method, 
Object, Object[]) line: not available [native method]   
            NativeMethodAccessorImpl.invoke(Object, 
Object[]) line: 39   
            DelegatingMethodAccessorImpl.invoke(Object, 
Object[]) line: 25   
            Method.invoke(Object, Object...) line: 597   
            FrameworkMethod$1.runReflectiveCall() line: 
44   
            FrameworkMethod$1(ReflectiveCallable).run() 
line: 15   
            FrameworkMethod.invokeExplosively(Object, 
Object...) line: 41   
            InvokeMethod.evaluate() line: 20   
            RunBefores.evaluate() line: 28   
            RunBeforeTestMethodCallbacks.evaluate() line: 
74   
            RunAfters.evaluate() line: 31   
            RunAfterTestMethodCallbacks.evaluate() line: 
82   
            SpringRepeat.evaluate() line: 72   
            
SpringJUnit4ClassRunner.runChild(FrameworkMethod, 
RunNotifier) line: 240   
            
SpringJUnit4ClassRunner(BlockJUnit4ClassRunner).runChild(Object, 
RunNotifier) line: 50   
            ParentRunner$3.run() line: 193   
            ParentRunner$1.schedule(Runnable) line: 52   
            
SpringJUnit4ClassRunner(ParentRunner<T>).runChildren(RunNotifier) 
line: 191   
            ParentRunner<T>.access$000(ParentRunner, 
RunNotifier) line: 42   
            ParentRunner$2.evaluate() line: 184   
            RunBeforeTestClassCallbacks.evaluate() line: 
61   
            RunAfterTestClassCallbacks.evaluate() line: 
70   
            
SpringJUnit4ClassRunner(ParentRunner<T>).run(RunNotifier) 
line: 236   
            SpringJUnit4ClassRunner.run(RunNotifier) line: 
180   
            
JUnit4TestClassReference(JUnit4TestReference).run(TestExecution) 
line: 46   
            TestExecution.run(ITestReference[]) line: 
38   
            RemoteTestRunner.runTests(String[], String, 
TestExecution) line: 467   
            RemoteTestRunner.runTests(TestExecution) line: 
683   
            RemoteTestRunner.run() line: 390   
            RemoteTestRunner.main(String[]) line: 197   
        Thread [ReaderThread] (Running)   
        Thread [org.subethamail.smtp.server.SMTPServer] 
(Running)   
        Thread 
[org.subethamail.smtp.server.Session-/127.0.0.1:3601] 
(Running)