Irule that waits?

Hi, I am afraid this it not possible for the moment

What about the following?

{set delay_count 0} {$delay_count<50000} {incr delay_count} {...

I'm not sure this iRule will not have some important performance impact on the cpu

 

 

i'll try to check it tomorrow if i have some time

No, it's not possible to do this. iRule execution is single-threaded, so if you did somehow pause execution (like run a tight wait-loop as someone suggested), then you would be holding up all other packet processing. The multiple watchdogs on the LTM would notice this, and take appropriate action (restart tmm, or failover, or reboot, or some combination thereof). So you don't want to do that. Could you explain what you're really wanting to do? Perhaps we can find some different way of accomplishing it.

Is it not possible because some has tried it?

 

 

/CB

 

 

 

It's less that it's "not possible", and more that it's just a really bad idea.

 

 

I've written a similar irule, to simulate a WAN environment. But as stated, you end up forcing ALL other traffic processing through the BIG-IP (all VIPs, all nodes, etc.) to wait while you cycle through this loop until the delay is completed.

 

 

Very, very bad.

 

 

Colin

Okay somehow it just clicked in my head on what spark stated "...holding up ALL OTHER packet processing". I never realized that iRules is single-threaded. Why was it designed that way?

Excellent. Thanks for the Info

As Colin said, tmm execution (and therefore iRule execution) is single-threaded. This was done for a variety of reasons, not the least of which is that you can be guaranteed that nothing else will happen while an iRule event is executing, so users don't have to worry about (e.g.) mutex locking on global variable accesses. No other connection can stomp on your global data in the middle of you accessing it. CMP introduces some complexities into this; likely someone will have to write an article on this sometime soon.

thanks again.