Hi, I'm hoping maybe this problem looks familiar to somebody out there..
I'm using Restlet 2.1.4 on GAE, and I'm seeing intermittent NPEs with the
(partial) stack trace below. This is happening on about 1% of requests.
17:00:19.465 org.restlet.engine.io.BioUtils getReader: The GAE edition is
unable to return a reader for a writer representation.
E 17:00:19.465 org.restlet.engine.adapter.ServerAdapter commit: An exception
occured writing the response entity
java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:78)
at java.io.BufferedReader.<init>(BufferedReader.java:94)
at
org.restlet.engine.io.ReaderInputStream.<init>(ReaderInputStream.java:101)
at org.restlet.engine.io.BioUtils.getStream(BioUtils.java:354)
at
org.restlet.representation.CharacterRepresentation.getStream(CharacterRepresentation.java:70)
at
org.restlet.util.WrapperRepresentation.getStream(WrapperRepresentation.java:151)
at
org.restlet.engine.application.RangeRepresentation.getStream(RangeRepresentation.java:117)
at
org.restlet.engine.application.RangeRepresentation.write(RangeRepresentation.java:146)
at
org.restlet.engine.adapter.ServerCall.writeResponseBody(ServerCall.java:510)
at
org.restlet.engine.adapter.ServerCall.sendResponse(ServerCall.java:454)
In the full stack trace further below, I've interspersed the source code at
each stack level. Here's my analysis so far:
The Reader constructor has received a null "lock" parameter from its caller.
BufferedReader is just passing its first argument ("in", a Reader) to super, so
"in" must be null.
which means that in ReaderInputStream's constructor, "reader" is null
which means that in BioUtils.getStream, "reader" (its first arg) is null
which means that in CharacterRepresentation.getStream, getReader() is returning
null
CharacterRepresentation is abstract and doesn't implement getReader, so its
implementation is coming from one of its subclasses.
Since it is getting called from WrapperRepresentation.getStream, that indicates
that the CharacterRepresentation is a wrapped representation.
Since that is getting called from RangeRepresentation.getStream, we know that
the wrapper is a RangeRepresentation, although we don't know what the wrapped
representation is (other than it is derived from CharacterRepresentation)
Since that is getting called from ServerCall.writeResponseBody, for the object
"entity", we know that "entity" is a RangeRepresentation.
The problem is that I'm expecting "entity" to be a JacksonRepresentation, not a
RangeRepresentation. And I can't find any code that instantiates a
RangeRepresention outside of RangeFilter, which I'm not using (to my knowledge).
Any ideas?
-Andy
W 17:00:19.465 org.restlet.engine.io.BioUtils getReader: The GAE edition is
unable to return a reader for a writer representation.
E 17:00:19.465 org.restlet.engine.adapter.ServerAdapter commit: An exception
occured writing the response entity
java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:78)
protected Reader(Object lock) {
if (lock == null) {
throw new NullPointerException();
at java.io.BufferedReader.<init>(BufferedReader.java:94)
super(in);
at
org.restlet.engine.io.ReaderInputStream.<init>(ReaderInputStream.java:101)
reader = (reader instanceof BufferedReader) ? (BufferedReader) reader : new
BufferedReader(reader, IoUtils.BUFFER_SIZE);
at org.restlet.engine.io.BioUtils.getStream(BioUtils.java:354)
result = new ReaderInputStream(reader, characterSet);
at
org.restlet.representation.CharacterRepresentation.getStream(CharacterRepresentation.java:70)
return BioUtils.getStream(getReader(), getCharacterSet());
at
org.restlet.util.WrapperRepresentation.getStream(WrapperRepresentation.java:151)
return getWrappedRepresentation().getStream();
at
org.restlet.engine.application.RangeRepresentation.getStream(RangeRepresentation.java:117)
return new RangeInputStream(super.getStream(), getSize(), getRange());
at
org.restlet.engine.application.RangeRepresentation.write(RangeRepresentation.java:146)
BioUtils.copy(getStream(), outputStream);
at
org.restlet.engine.adapter.ServerCall.writeResponseBody(ServerCall.java:510)
entity.write(responseEntityStream);
at
org.restlet.engine.adapter.ServerCall.sendResponse(ServerCall.java:454)
at
org.restlet.ext.servlet.internal.ServletCall.sendResponse(ServletCall.java:459)
at
org.restlet.engine.adapter.ServerAdapter.commit(ServerAdapter.java:196)
at
org.restlet.engine.adapter.HttpServerHelper.handle(HttpServerHelper.java:153)
at
org.restlet.ext.servlet.ServerServlet.service(ServerServlet.java:1089)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at
com.googlecode.objectify.cache.AsyncCacheFilter.doFilter(AsyncCacheFilter.java:59)
at
com.googlecode.objectify.ObjectifyFilter.doFilter(ObjectifyFilter.java:49)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at
com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:266)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at
org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at
com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at
com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:146)
at
com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:446)
at
com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
at
com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
at
com.google.tracing.CurrentContext.runInContext(CurrentContext.java:188)
at
com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
at
com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
at
com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
at
com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
at java.lang.Thread.run(Thread.java:724)
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