Pstack

All

Intro

Debug using gdb for Apache

Pstack

pstack is this quite an interesting tool for debugging in case you don’t want to trace the server.  Basically this command command shows a stack trace for each process!! Similar to gstack but for RHEL.

pstack <pid>

Example stolen from Oracle to demonstrate nfsd

243:    /usr/lib/nfs/nfsd -a 16
 ef675c04 poll     (24d50, 2, ffffffff)
 000115dc ???????? (24000, 132c4, 276d8, 1329c, 276d8, 0)
 00011390 main     (3, efffff14, 0, 0, ffffffff, 400) + 3c8
 00010fb0 _start   (0, 0, 0, 0, 0, 0) + 5c

 

On this case we can see that last function is pool, called from ??? – without ELF info – which was called by main.

Reading

The reading follows the simple rule:

 The bottom is the start –> the top is the last call 

REFs

  inline

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