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20040802: LDM pqact child Core Dump Problem

Kevin,

The child of pqact is most probably a decoder or script that you
are piping to from pqact. If you have a core file, the comand "file
core" will tell you what process created it- or check your decoder logs
and see if you can match the process ID with the child process. 
You can cycle pqact into verbose mode (using the -USR2 fignal)
to get a line by line listing of pqact if you need tosee each action
being processed to track down the child.

One common problem with decoders is having more than one instance
writing to the output file, which can occur if your
system if falling behind. In this case, you would also probably notice
pbuf messages in your LDM logs. A second -USR2 signal to pqact will
cycle logging into debug mode. You would see "delay" messages there
indicating how long it takes to process products in the queue.
If the delay time is climbing, it also would signal that your
products are backing up.

Steve Chiswell
Unidata User Support


On Mon, 2004-08-02 at 12:02, Kevin W. Thomas wrote:
> Hi...
> 
> Recently, while looking over some ETA and NEXRAD files received via LDM I
> noticed that there were periods when data was lost.  After doing lots of
> checking around, with the help of a local System Administrator, I discovered
> that them data gaps are strongly correlated with the message:
> 
>       pqact[pid]: child ##### terminated by signal 11
> 
> Signal 11 is "segmentation violation".
> 
> I have a second LDM system running a similar ingest configuration.  Checking
> its log files shows the same problem.
> 
> Both systems are Intel, though I don't know what cpu's.  Both run RedHat 9.x.
> The first has logged 29 seg faults today, with the second logging 16.  There
> are no common times in either log.
> 
> I checked another Intel machine, unknown version of RedHat, probably 7.x or
> 9.x, that had been running LDM a few months ago.  It had 30 on the last full
> day of operation at that system.
> 
> Everything is running LDM 6.0.14.
> 
> Any ideas would be greatly appreciated.
> 
>       Kevin W. Thomas
>       Center for Analysis and Prediction of Storms
>       University of Oklahoma
>       Norman, Oklahoma
>       Email:  address@hidden