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-   -   CADO-NFS Square Root Error (https://www.mersenneforum.org/showthread.php?t=24902)

Ferrier 2019-11-01 04:21

CADO-NFS Square Root Error
 
I was trying to factor a c155, everything went well until:

[CODE]
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

[/CODE]

I tried resume, but the same issue.

chris2be8 2019-11-01 16:43

Hello,

The message that jumps out at me is:
[quote]
Error:Square Root: fork: Cannot allocate memory
[/quote]

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 2019-11-01 20:13

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 2019-11-01 23:51

[QUOTE=chris2be8;529417]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[/QUOTE]

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!


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