IBM Support

How to read HP Verbose GC Log? what are the different columns?

Question & Answer


Question

How to read HP Verbose GC Log? what are the different columns?

Answer

-Xverbosegc sends log information to stderr by default.
The following command line sends -Xverbosegc output to a text file named yourApp_pid<pid>.vgc:
java -Xverbosegc:file=yourApp_pid<pid>.vgc yourApp
At every garbage collection 20 fields are printed as follows:
GC: %1 %2 %3 %4 %5 %6 %7 %8 %9 %10 %11 %12 %13 %14 %15 %16 %17 %18 %19 %20
The following table contains brief descriptions of these 20 fields:
   <thead>                                            </thead>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
           
Field
           		            
Information in Field
           
           
1
           		            
Type of GC:
           
                   
  • 1: Scavenge (GC of New Generation only)
    •                
  • 2: Old Generation GC or a Full GC
    •                
  • 3: Complete background CMS GC
    •                
  • 4: Incomplete background CMS GC
    •                
  • 11: Ongoing CMS GC
    •            
           
           
2
           		            
Additional information based on GC type in field 1.
           
           
3</ div>            
            
Program time at the beginning of the GC, in seconds.
           
           
4
           		            
GC invocation. Counts of background CMS GCs and other GCs are maintained separately.
           
           
5
           		            
Size of the object allocation request that forced the GC, in bytes.
           
           
6
           		            
Tenuring threshold—determines how long the newborn object remains in the New Generation.
           
           
7
           		            
Eden Sub-space (within the New Generation) occupied before GC.
           
           
8
           		            
Eden Sub-space (within the New Generation) occupied after GC.
           
           
9
           </ td>            		            
Eden Sub-space (within the New Generation) current capacity.
           
           
10
           		            
Survivor Sub-space (within the New Generation) occupied before GC.
           
           
11
           		            
Survivor Sub-space (within the New Generation) occupied after GC.
           
           
12
           		            
Survivor Sub-space (within the New Generation) current capacity.
           
           
13
           		            
Old Generation occupied before GC.
           
           
14
           		            
Old Generation occupied after GC.
           
           
15
           </ td>            		            
Old Generation current capacity.
           
           
16</ div>            
            
Permanent Generation (storage of Reflective Objects) occupied before GC.
           
           
17
           </ td>            		            
Permanent Generation (storage of Reflective Objects) occupied after GC.
           
           
18
           		            
Permanent Generation (storage of Reflective Objects) current capacity.
           
           
19
           		            
The total stop-the-world duration, in seconds.
           
           
20
           		            
The total time used in collection, in seconds.
           
Example:
<GC: <u>2 1</u> 174206.339748 79</div> <div> </div> <div> </div> <div>In the above gc log, first one shows it is a full gc; second one shows it is perm gc.</div> <p>

[{"Product":{"code":"SS6PEW","label":"IBM Sterling Order Management"},"Business Unit":{"code":"BU048","label":"IBM Software"},"Component":"Not Applicable","Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"All","Edition":"","Line of Business":{"code":"LOB59","label":"Sustainability Software"}}]

Historical Number

HTG2328

Document Information

Modified date:
16 June 2018

UID

swg21562190

Page Feedback