Viewing GC Analysis Results

Prerequisites

A sampling analysis task has been created and the analysis is complete.

Procedure

1. In the Task/Report List area of the Java Profiler page, click the name of the analysis task under Sampling Profiling.

   The Overview tab page is displayed.

2. Click the GC tab.
   The GC analysis result is displayed, as shown in Figure 1 and Figure 2. For details about the parameters, see Table 1.

   

   You can click View Details after to view the tuning suggestions for the current task.

   Figure 1 GC
   
   Figure 2 GC tab page – Collected GC Event Info
   

   Table 1 Parameters on the GC tab page

   Parameter	Description
   GC Configuration
   YoungCollector	Name of the young-generation garbage collector.
   OldCollector	Name of the old-generation garbage collector.
   ConcGCThreads	Number of concurrent GC threads.
   ParallelGCThreads	Number of parallel GC threads.
   ExplicitGCInvokesConcurrent	Indicates whether concurrent execution of GC is enabled.
   DisableExplicitGC	Indicates whether triggering GC is disabled.
   UseDynamicNumberOfGCThreads	Indicates whether the function of dynamically adjusting the number of GC threads is enabled.
   GCTimeRatio	Ratio of the garbage collection time to the total time.
   Heap Configuration
   InitialHeapSize	Size of the initial heap.
   MinHeapSize	Size of the smallest heap.
   MaxHeapSize	Size of the largest heap.
   UseCompressedOops	Indicates whether compressed Oops is enabled.
   PrintCompressedOopsMode	Compressed Oops mode in use.
   heapAddressBits	Size of the heap address.
   ObjectAlignmentInBytes	Memory alignment (in bytes) of Java objects.
   Young Generation Configuration
   NewSize	Minimum size of the young generation.
   MaxNewSize	Maximum size of the young generation.
   NewRatio	Ratio of the young generation size to the old generation size.
   InitialTenuringThreshold	Initial number of times that an old-generation object alive in the young generation.
   MaxTenuringThreshold	Maximum number of times that an old-generation object alive in the young generation.
   UseTLAB	Indicates whether the thread local allocation buffer (TLAB) is enabled.
   MinTLABSize	TLAB size.
   TLABRefillWasteFraction	Memory size that can be wasted by the TLAB.
   GC Activities
   GC Activity	GC activity ID.
   Cause	Cause of GC.
   Collector Name	Name of the garbage collector.
   Memory Before GC	Memory capacity before GC.
   Memory After GC	Memory capacity after GC.
   Max Pause Duration	Maximum time for which the GC is paused.
   Pause Phase
   Event Type	Event type in the pause phase.
   Name	Name of the pause phase.
   Pause Time (µs)	Pause duration.
   Start Time	Start time of the pause phase.
   Collected GC Event Info
   Pause Time (ms)	Pause duration.
   Heaps (MiB)	Heap memory size.
   Metaspace (MiB)	Metaspace size.