Re: [Chromium-dev] Chromium start-up time

[Brian P. <bri...@tu...>]

Brian Paul wrote:
> aac...@ad... wrote:
> 
>> Hi,
>>
>> We currently have a 20 node display that we use with Chromium.  All 20 
>> nodes, including the Mothership and CRAppfaker run on Windows through 
>> Cygwin. 
>> I won't go into excruciating detail about our configuration except to 
>> say that we use one TileSort spu and 20 render spu's, that are added 
>> and configured through their appropriate nodes.
>>
>> The problem we noticed is that the start-up time to initialize all 20 
>> displays, plus the CRAppfaker with the Mothership was extremely slow, 
>> taking more than 3 minutes execution time.
>>
>> I traced at least part of the problem down to the Mothership.py file 
>> and the __qualifyHostname__ function.  It was spending 4.5 seconds to 
>> sit on the call to socket.getfqdn(host).  We did not have DNS set up 
>> so I believe it was sitting on this call to fully qualify the host 
>> name and timing out after 4-4.5 seconds.  Also, this function was 
>> being called twice per display node via the do_acceptrequest and 
>> do_connectrequest functions.  Therefore, this was adding alot of time 
>> to wait for all of the displays to initialize.  Could you please 
>> explain why it needs to fully qualify the name??  I'm not sure I 
>> understand why it needs to do this since if we just return immediately 
>> with the hostname that is passed in, it works just fine. 
>> Thanks,
>> Alicia
> 
> 
> It looks like that code was a patch from Joel Welling that I checked in 
> last December.
> 
> Maybe Joel can provide some info.

Joel replied and asked that I forward this info to the list:



> Well, __qualifyHostname__() does a table lookup, which should be quite fast.  
> If it fails to find the hostname in that list (__hostPrefixPairs__) it does a 
> socket.getfqdn(host).  I had to add the lookup to facilitate connecting to 
> Argonne's vis nodes from outside.  I believe the socket.getfqdn() was in the 
> server logic before my mod, but not separated off into the 
> __qualifyHostname__() function.
> 
> The cost of taking out the socket.getfqdn() would be that we'd be making 
> connections based on local domain names instead of global ones, and that would 
> surely not be good for non-local Chromium networks.  I presume it works fine 
> for Alicia without the fqdn is that her network is local and all her hosts are 
> in each other's /etc/hosts tables (or the Windows equivalent).
> 
> I remember some discussion about this a while back, but I don't have time at 
> the moment to search the archives for it.  Alicia, if you don't want to 
> disable the socket.getfqdn(host) code and if your hostnames have a common 
> prefix like 'vis', you could add them to __hostPrefixPairs__ as a temporary 
> work-around.


If the fqdn() hostname lookup is a real problem, perhaps we could add 
a configuration option to enable/disable it.  Something like:

	cr = CR()
	cr.Conf("fully_qualify_domain_names", 0)


-Brian