Details
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Bug
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Status: Resolved
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Minor
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Resolution: Fixed
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3.0.0
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None
Description
While starting some local tests, I occasionally encountered the following exceptions for Web UI.
23:00:29.845 WARN org.eclipse.jetty.server.HttpChannel: /jobs/ java.util.NoSuchElementException at java.util.Collections$EmptyIterator.next(Collections.java:4191) at org.apache.spark.util.kvstore.InMemoryStore$InMemoryIterator.next(InMemoryStore.java:467) at org.apache.spark.status.AppStatusStore.applicationInfo(AppStatusStore.scala:39) at org.apache.spark.ui.jobs.AllJobsPage.render(AllJobsPage.scala:266) at org.apache.spark.ui.WebUI.$anonfun$attachPage$1(WebUI.scala:89) at org.apache.spark.ui.JettyUtils$$anon$1.doGet(JettyUtils.scala:80) at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:873) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1623) at org.apache.spark.ui.HttpSecurityFilter.doFilter(HttpSecurityFilter.scala:95) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1610) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:540) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1345) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:480) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1247) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144) at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:753) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:220) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) at org.eclipse.jetty.server.Server.handle(Server.java:505) at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:370) at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:267) at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:305) at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103) at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:698) at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:804) at java.lang.Thread.run(Thread.java:748)
Reason
That is because AppStatusStore.applicationInfo() accesses an empty view (iterator) returned by InMemoryStore.
AppStatusStore
def applicationInfo(): v1.ApplicationInfo = {
store.view(classOf[ApplicationInfoWrapper]).max(1).iterator().next().info
}
InMemoryStore
public <T> KVStoreView<T> view(Class<T> type){ InstanceList<T> list = inMemoryLists.get(type); return list != null ? list.view() : emptyView(); }
During the initialization of SparkContext, it first starts the Web UI (SparkContext: L475 ui.foreach(.bind())) and then setup the LiveListenerBus thread (SparkContext: L608 setupAndStartListenerBus()) for dispatching the SparkListenerApplicationStart event (which will trigger writing the requested ApplicationInfo to InMemoryStore).
