[Pvfs2-developers] server crash on startup with millions of files

[Phil Carns]

Phil Carns wrote:
>> Yeah that is odd.  Setting the cursor for each call to  
>> iterate_handles may be the reason for it starting over.  Do you know  
>> how many times it starts over?  The number of times iterate_handles  
>> is called will be (# of files / 4096).
> 
> 
> It only goes through the file twice if I am looking at the log 
> correctly.  Also, I just realized that on both passes (the one jumping 
> backwards 40KB at a time and the one jumping backwards 4KB at a time) it 
> is only reading 4KB per pread.  I don't know what it is doing from a db 
> point of view, but from an access point of view it looks like it goes 
> backwards with a strided pattern and then goes backwards reading the 
> entire thing.  There are some other reads scattered here and there, but 
> those two cycles represent the overwhelming majority of the total preads 
> in the strace file.  By spot checking I don't really see any significant 
> divergence from the patterns.
> 
> It also just occurred to me that maybe I should repeat the strace and 
> try to capture it with timestamps; I'm not really sure if both of these 
> pread cycles are actually during the scan or not.
> 

I just double checked- both of those big pread cycles are happening 
after this message is logged:

[D 13:06:53.916769] dbpf collection 752900094 - Setting collection 
handle ranges to 4-536870914,4294967292-4831838202

... but before the next message.  So they do appear to both be a result 
of the handle scanning on startup.

-Phil