Details
Critical Description
When MapContext is used anywhere (eg FlexibleStringExpander) and the context contains ByteBuffer objects (either key or value), java will slow down when calling MapContext.entrySet().
Here is the code in ofbiz, highlighted is the line of code that I believe is the culprit
MapContext.java
public Set<Map.Entry<K, V>> entrySet() { // walk the stackList and the entries for each Map and if nothing is in for the current key, put it in Set<K> resultKeySet = new HashSet<K>(); culprit --> Set<Map.Entry<K, V>> resultEntrySet = new ListSet<Map.Entry<K, V>>(); for (Map<K, V> curMap: this.stackList) { for (Map.Entry<K, V> curEntry: curMap.entrySet()) { if (!resultKeySet.contains(curEntry.getKey())) { resultKeySet.add(curEntry.getKey()); resultEntrySet.add(curEntry); } } } return Collections.unmodifiableSet(resultEntrySet); }
Looking at the java api for Map.Entry, the hashCode method for Map.Entry is the result of the hashCode from both key and value. ByteBuffer hash code is dependent upon its content. If a 2mb file is uploaded, the hashCode method
of ByteBuffer will scan 2mb to generate the hashCode
ByteBuffer
http://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html#hashCode()
Because buffer hash codes are content-dependent, it is inadvisable to use buffers as keys in hash maps or similar data structures unless it is known that their contents will not change.
Map.Entry
http://docs.oracle.com/javase/7/docs/api/java/util/Map.Entry.html#hashCode()
(e.getKey()==null ? 0 : e.getKey().hashCode()) ^ (e.getValue()==null ? 0 : e.getValue().hashCode())
HashSet
http://docs.oracle.com/javase/7/docs/api/java/util/HashSet.html
This class implements the Set interface, backed by a hash table (actually a HashMap instance
Example where ByteBuffer objects are created
org.ofbiz.webapp.event.ServiceEventHandler
Example stack trace
"ajp-bio-8009-exec-1894" daemon prio=10 tid=0x00007fa52c070000 nid=0x5c73 runnable [0x00007fa51151b000] java.lang.Thread.State: RUNNABLE at java.nio.HeapByteBuffer.ix(HeapByteBuffer.java:131) at java.nio.HeapByteBuffer.get(HeapByteBuffer.java:139) at java.nio.ByteBuffer.hashCode(ByteBuffer.java:1083) at java.util.Objects.hashCode(Objects.java:96) at java.util.HashMap$Entry.hashCode(HashMap.java:847) at java.util.AbstractMap.hashCode(AbstractMap.java:494) at java.util.Objects.hashCode(Objects.java:96) at java.util.HashMap$Entry.hashCode(HashMap.java:847) at java.util.HashMap.hash(HashMap.java:362) at java.util.HashMap.put(HashMap.java:492) at java.util.HashSet.add(HashSet.java:217) at org.ofbiz.base.util.collections.MapContext.entrySet(MapContext.java:306) at java.util.HashMap.putAll(HashMap.java:642) at org.ofbiz.widget.model.ModelFormField$ListOptions.addOptionValues(ModelFormField.java:2716) at org.ofbiz.widget.model.ModelFormField$FieldInfoWithOptions.getAllOptionValues(ModelFormField.java:1985) at org.ofbiz.widget.renderer.macro.MacroFormRenderer.renderDropDownField(MacroFormRenderer.java:747) at org.ofbiz.widget.model.ModelFormField$DropDownField.renderFieldString(ModelFormField.java:1739) at org.ofbiz.widget.model.ModelFormField.renderFieldString(ModelFormField.java:693) at org.ofbiz.widget.renderer.FormRenderer.renderSingleFormString(FormRenderer.java:1195) at org.ofbiz.widget.renderer.FormRenderer.render(FormRenderer.java:261) at org.ofbiz.widget.model.ModelScreenWidget$Form.renderWidgetString(ModelScreenWidget.java:1052) at org.ofbiz.widget.renderer.macro.MacroScreenRenderer.renderScreenletSubWidget(MacroScreenRenderer.java:677) at org.ofbiz.widget.model.ModelScreenWidget$Screenlet.renderWidgetString(ModelScreenWidget.java:598) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.ofbiz.widget.model.ScreenFactory.renderReferencedScreen(ScreenFactory.java:211) at org.ofbiz.widget.model.ModelScreenWidget$IncludeScreen.renderWidgetString(ModelScreenWidget.java:779) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Container.renderWidgetString(ModelScreenWidget.java:459) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorSection.renderWidgetString(ModelScreenWidget.java:905) at org.ofbiz.widget.model.ModelScreenWidget$SectionsRenderer.render(ModelScreenWidget.java:127) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorSectionInclude.renderWidgetString(ModelScreenWidget.java:942) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorSection.renderWidgetString(ModelScreenWidget.java:905) at org.ofbiz.widget.model.ModelScreenWidget$SectionsRenderer.render(ModelScreenWidget.java:127) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorSectionInclude.renderWidgetString(ModelScreenWidget.java:942) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorSection.renderWidgetString(ModelScreenWidget.java:905) at org.ofbiz.widget.model.ModelScreenWidget$SectionsRenderer.render(ModelScreenWidget.java:127) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorSectionInclude.renderWidgetString(ModelScreenWidget.java:942) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Container.renderWidgetString(ModelScreenWidget.java:459) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Container.renderWidgetString(ModelScreenWidget.java:459) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Container.renderWidgetString(ModelScreenWidget.java:459) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.ofbiz.widget.model.ScreenFactory.renderReferencedScreen(ScreenFactory.java:211) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorScreen.renderWidgetString(ModelScreenWidget.java:859) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.ofbiz.widget.model.ScreenFactory.renderReferencedScreen(ScreenFactory.java:211) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorScreen.renderWidgetString(ModelScreenWidget.java:859) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.ofbiz.widget.model.ScreenFactory.renderReferencedScreen(ScreenFactory.java:211) at org.ofbiz.widget.model.ModelScreenWidget$DecoratorScreen.renderWidgetString(ModelScreenWidget.java:859) at org.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.ofbiz.widget.renderer.ScreenRenderer.render(ScreenRenderer.java:136) at org.ofbiz.widget.renderer.ScreenRenderer.render(ScreenRenderer.java:98) at org.ofbiz.widget.renderer.macro.MacroScreenViewHandler.render(MacroScreenViewHandler.java:157) at org.ofbiz.webapp.control.RequestHandler.renderView(RequestHandler.java:989) at org.ofbiz.webapp.control.RequestHandler.doRequest(RequestHandler.java:676) at org.ofbiz.webapp.control.ControlServlet.doGet(ControlServlet.java:221) at org.ofbiz.webapp.control.ControlServlet.doPost(ControlServlet.java:89) at javax.servlet.http.HttpServlet.service(HttpServlet.java:646) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.ofbiz.webapp.control.ContextFilter.doFilter(ContextFilter.java:321) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421) at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:190) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314) - locked <0x00000006f95b1cf0> (a org.apache.tomcat.util.net.SocketWrapper) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)
The solution would be not to use HashSet but instead a simpler Set class such as a Set backed by a List.