bug in logging code?

[Mark Nelson <mark.a.nelson@gmail.com>]

I've been playing around with usng the various write_*_log options in 
fio to record run statistics.  What I'm finding is that some of the logs 
have malformed lines in them.  The following snippet is from the bw log:

811820, 12263, 0, 4194304
812619, 35929, 0, 4194304
818437, 8448, 0, 419430, 4194304
1256299, 160627, 0, 4194304
1256831, 154274, 0, 4194304

Notice that the malformed line appears to be a partial write that gets 
truncated.  The fio command being used to run the tests is 
autogenerated, so job files aren't used.  here's the one that created 
the above log snippet:

/home/nhm/bin/fio
--rw=read
--ioengine=libaio
--runtime=7200
--ramp_time=0
--numjobs=1
--direct=1
--bs=4194304B
--iodepth=16
--size=9216M
--write_iops_log=/tmp/cbt/ceph/kvmrbdfio/osd_ra-00004096/client_ra-00000128/op_size-04194304/concurrent_procs-008/iodepth-016/read/output 

--write_bw_log=/tmp/cbt/ceph/kvmrbdfio/osd_ra-00004096/client_ra-00000128/op_size-04194304/concurrent_procs-008/iodepth-016/read/output 

--write_lat_log=/tmp/cbt/ceph/kvmrbdfio/osd_ra-00004096/client_ra-00000128/op_size-04194304/concurrent_procs-008/iodepth-016/read/output 

--time_based
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-0
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-1
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-2
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-3
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-4
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-5
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-6
--name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-7

The --numjobs=1 line should be removed, but I believe it gets overridden 
anyway with multiple name parameters.  I wonder if having multiple name 
parameters (ie multiple fio processes) is causing those processes to all 
try to write to the same log files, potentially at the same time?  Any 
thoughts would be much appreicated!

Thanks,
Mark