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Server Details:
Kernel: Linux wiq31 2.4.21-9.ELsmp #1 SMP Thu Jan 8 17:08:56 EST 2004 i686 i686 i386 GNU/Linux
CPU: 4 x Intel(R) Xeon(TM) CPU 3.06GHz
Memory: 1028520 kB
JBoss version: 3.2.7

Every time i try to start JBoss, in all CPU's, the iowait values starts to raise and the idle values starts to fall.

Before executing my JBoss application, the free command returns the following output:

             *total       used       free     shared    buffers     cached  
Mem:       1028520     966400      62120          0     187756     538928  
-/+ buffers/cache:     239716     788804  
Swap:      2044072     790672    1253400*  

After starting my JBoss application, the free command returns the following output:

             *total       used       free     shared    buffers     cached  
Mem:       1028520    1007648      20872          0     187116     524084  
-/+ buffers/cache:     296448     732072  
Swap:      2044072     819096    1224976*  

After starting my JBoss application, without answering any request, the java process /proc/PID/status file have the following values:

State:  S (sleeping)
SleepAVG:       27%
Tgid:   24022
Pid:    24022
PPid:   21011
TracerPid:      0
Uid:    500     500     500     500
Gid:    500     500     500     500
FDSize: 256
Groups: 500
VmSize:   775200 kB
VmLck:         0 kB
VmRSS:    156752 kB
VmData:   696752 kB
VmStk:        36 kB
VmExe:        21 kB
VmLib:    710375 kB
StaBrk: 0804f000 kB
Brk:    095bb000 kB
StaStk: bffff8c0 kB
ExecLim:        ffffffff
Threads:        62
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000000000
SigCgt: 1000000180015ccf
CapInh: 0000000000000000
CapPrm: 0000000000000000
CapEff: 0000000000000000

Is this behavior being caused by memory swapping, or the short memory available in the server is enough to run my application?

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1 Answer 1

Jboss will take up a pretty significant amount of memory on its own, even if you don't have anything running on it.

To see if your system is heavily swapping, you can always run

vmstat 1

and watch the output. Under "swap", you'll see "si" and "so"-- thos will be pages swapped in and out.

At a guess I would suggest more RAM, but you should really to move investigation first. For instance, if you have a lot of big objects being deployed, you may just need to wait on jboss for a while to drag these objects off the disk.

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