CADO-NFS Square Root Error

[Ferrier]

I was trying to factor a c155, everything went well until:

Info:Linear Algebra: Starting
Info:Linear Algebra: Total cpu/real time for bwc: 171995/12675.5
Info:Linear Algebra: Aggregate statistics:
Info:Linear Algebra: Krylov: WCT time 7918.53, iteration CPU time 0.04, COMM 0.01, cpu-wait 0.02, comm-wait 0.0 (114000 iterations)
Info:Linear Algebra: Lingen CPU time 1287.91, WCT time 103.11
Info:Linear Algebra: Mksol: WCT time 4285.51, iteration CPU time 0.05, COMM 0.01, cpu-wait 0.02, comm-wait 0.0 (57000 iterations)
Info:Quadratic Characters: Starting
Info:Quadratic Characters: Total cpu/real time for characters: 163.88/38.8057
Info:Square Root: Starting
Info:Square Root: Creating file of (a,b) values
Warning:Command: Process with PID 5600 finished with return code -11
Error:Square Root: Program run on server failed with exit code -11
Error:Square Root: Command line was: /root/Math/cado-nfs/build/c3c/sqrt/sqrt -poly ./snap/c155.poly -prefix ./snap/c155.dep.gz -purged ./snap/c155.purged.gz -index ./snap/c155.index.gz -ker ./snap/c155.kernel -dep 0 -t 8 -side0 -side1 -gcd > ./snap/c155.sqrt.stdout.5 2> ./snap/c155.sqrt.stderr.5
Error:Square Root: Stderr output (last 10 lines only) follow (stored in file ./snap/c155.sqrt.stderr.5):
Error:Square Root: 	Alg(3): start lifting mod p^39684643 (227310479 bits) at 2731.97s
Error:Square Root: 	Alg(2): start lifting mod p^39705131 (227427833 bits) at 2733.72s
Error:Square Root: 	Alg(4): start lifting mod p^39707377 (227440697 bits) at 2781.35s
Error:Square Root: 	Alg(6): start lifting mod p^39707446 (227441093 bits) at 2814.16s
Error:Square Root: 	Alg(5): start lifting mod p^39684923 (227312083 bits) at 2816.04s
Error:Square Root: 	Alg(0): start lifting mod p^39699533 (227395768 bits) at 2837.66s
Error:Square Root: 	Alg(7): maximal sqrt bit-size = 206709593 (91% of target size)
Error:Square Root: 	Alg(7): square root lifted in 2357.35s
Error:Square Root: 	fork: Cannot allocate memory
Error:Square Root:
Traceback (most recent call last):
  File "./cado-nfs.py", line 122, in <module>
    factors = factorjob.run()
  File "./scripts/cadofactor/cadotask.py", line 5885, in run
    last_status, last_task = self.run_next_task()
  File "./scripts/cadofactor/cadotask.py", line 5977, in run_next_task
    return [task.run(), task.title]
  File "./scripts/cadofactor/cadotask.py", line 4871, in run
    raise Exception("Program failed")
Exception: Program failed

I tried resume, but the same issue.

[chris2be8]

Hello,

The message that jumps out at me is:

Error:Square Root: fork: Cannot allocate memory

How much memory and swap space does the system have? Are there any system log messages about memory shortages? What else is running on the system?

HTH

Chris

[VBCurtis]

I also have had this error, and indeed the system was quite busy. I killed a few other tasks and freed up ~10GB of memory, and the sqrt finished without issue.
I'm not saying 10GB is needed; I don't recall what size task I was running, for one thing. But I'm pretty sure Chris is right and you were merely out of memory.

[Ferrier]

Originally Posted by chris2be8

Hello,

The message that jumps out at me is:


How much memory and swap space does the system have? Are there any system log messages about memory shortages? What else is running on the system?

HTH

Chris

That machine was 20 threads Intel Xeon Gold 6136 with 16GB Memory

This time I tried to resize the server to 16 threads with 32GB Memory, the highest hit was like about 12GB. And the result came out quickly with no error.

Thanks!