[Varnish] #1576: default pcre_match_limit_recursion and thread_pool_stack dont match - varnishd child process crashes with segfault error 6 in libpcre.so.3.13.1

[Varnish]

#1576: default pcre_match_limit_recursion and thread_pool_stack dont match -
varnishd child process crashes with segfault error 6 in libpcre.so.3.13.1
----------------------+--------------------
 Reporter:  abdi      |       Owner:  phk
     Type:  defect    |      Status:  new
 Priority:  normal    |   Milestone:
Component:  varnishd  |     Version:  4.0.1
 Severity:  normal    |  Resolution:
 Keywords:            |
----------------------+--------------------

Comment (by slink):

 summary of irc discussion:

 On estimating stack per pcre recursion:

 * we could dynamically determine the stack space required per pcre
 recursion: implement a bin search on the pcre recursion limit to determine
 the minimal recursion depth for some RE and pattern and take the actual
 stack size used on this. add a safety margin and take this as our
 stack_bytes / pcre_recursion measure.
   * but we consider this an overdesign for now
 * we could run `pcretest` from autocrap and get our stacksize estimate
 {{{
   pcretest -m -C
   [...]
   Match recursion uses stack: approximate frame size = 176 bytes
 }}}
   * trouble is that `pcretest` does not get installed with -dev packages
 on some distros (read: at least not on debian)
 * so we probably just start with 600 bytes

 The implementation should check the remaining stack space and set the pcre
 recursion limit accordingly

 On JIT: We'd want JIT as a per-RE flag only, not as a global flag

-- 
Ticket URL: <https://www.varnish-cache.org/trac/ticket/1576#comment:17>
Varnish <https://varnish-cache.org/>
The Varnish HTTP Accelerator