Resource usage in versions 1.7.2 and 1.8.0

marllos · August 22, 2022, 1:48am

Hello everyone. I updated Julia from version 1.7.2 to 1.8.0 and had a surprise: a code that used 2 GB of RAM, now uses 10 GB, and the number of subprocesses (htop) also increased from 8 to 64! Is this normal? I was a bit worried.

Oscar_Smith · August 22, 2022, 2:04am

That’s really concerning. Any chance you can give an example that reproduces the behavior? is there a corresponding speed increase? Also, how many cores does your system have?

marllos · August 22, 2022, 2:26am

Whenever I can, I make sample code, but in this case there is no way, because it is a big code. I still don’t know if it is more efficient, because the execution time varies a lot, between 12 and 24 hours. The system is a 64-core Ubuntu 20.04 server. On my notebook, with 4 cores and 8 GB of RAM this increase did not occur.

Oscar_Smith · August 22, 2022, 2:50am

Are you using a lot of matrix multiplies? I believe in 1.8 we increased the maximum number of BLAS threads.

marllos · August 22, 2022, 2:59am

Yes, I use the LinearAlgebra package a lot and make many products of ComplexF64 Hermitian matrices of dimensions 8x8x2x1000 and other smaller dimensions.

Oscar_Smith · August 22, 2022, 3:09am

Try lowering the number of BLAS threads. (or if you want your program to be faster use MKL)

marllos · August 22, 2022, 3:16am

Interesting: BLAS threads 1.7.2 = 8; 1.8.0 = 32. I’ll test it tomorrow and get back to you.

carstenbauer · August 22, 2022, 5:40am

Instead of just lowering the number of BLAS threads I recommend that you benchmark your code properly to see if using more BLAS threads gives you better performance (it probably should) as @Oscar_Smith said before. After all, if you have a 64 core system you typically don’t want to only use a small fraction of the cores.

Also, guessing from the number of cores (64), does this happen to be an AMD system? If yes, you might want to try BLISBLAS.jl or MKL.jl, see GitHub - carstenbauer/julia-dgemm-noctua: DGEMM Benchmarks on Noctua 1/2 at PC2.

marllos · August 22, 2022, 1:58pm

I used the command BLAS.set_num_threads(8) right after using LinearAlgebra, and it had no effect.

marllos · August 22, 2022, 1:59pm

Each run lasts an average of 18 hours, so it is hard to benchmark, but I will try anyway. I think it is great when I can use many cores, but I can’t always, because of other users.

marllos · August 22, 2022, 2:01pm

Julia Version 1.8.0
Commit 5544a0fab76 (2022-08-17 13:38 UTC)
Platform Info:
OS: Linux (x86_64-linux-gnu)
CPU: 64 × AMD EPYC 7452 32-Core Processor
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-13.0.1 (ORCJIT, znver2)
Threads: 1 on 64 virtual cores

Oscar_Smith · August 22, 2022, 2:01pm

For initial testing, you should probably start by just testing the speed of complex hermitian matrix multiplication.

Palli · August 22, 2022, 2:20pm

Could you try in Julia 1.9-DEV nightly? E.g. with:

julia --heap-size-hint=2GB

I would at least be intrigued to know if this new option, from 1.9 NEWS, helps:

New option --heap-size-hint=<size> gives a memory hint for triggering greedy garbage collection. The size might be specified in bytes, kilobytes(1000k), megabytes(300M), gigabytes(1.5G)

The input and output is the same (size), only some temporary intermediate computation larger, so this should help? Eventually with better GC wouldn’t be needed, and also we will all have 10 GB+ in the future, it will be peanuts…

digital_carver · August 22, 2022, 3:08pm

From the text you posted from NEWS.md, it seems like it should be

julia --heap-size-hint=2G

(i.e. without the B)

marllos · August 22, 2022, 3:23pm

And where do I download Julia 1.9-DEV nightly, I download it from
Nightly builds but it didn’t work, I got the error:
/usr/local/bin/julia301b62ae73: cannot execute binary file: Exec format error

Palli · August 23, 2022, 8:56am

Maybe missing chmod, or see here:

Did you for sure download the right binary?

My somewhat older 1.9-DEV ~~worked~~ didn’t complain with:

julia --heap-size-hint=2GB

But it’s a good catch, it might not work if I’m reading the code correctly:

github.com

JuliaLang/julia/blob/bd26069cee94bda2b7dec498a6bf92fb2aff76d7/src/jloptions.c#L770


      
              jl_options.strip_metadata = 1;
              break;
          case opt_strip_ir:
              jl_options.strip_ir = 1;
              break;
          case opt_heap_size_hint:
              if (optarg != NULL) {
                  size_t endof = strlen(optarg);
                  long double value = 0.0;
                  if (sscanf(optarg, "%Lf", &value) == 1 && value > 1e-7) {
                      char unit = optarg[endof - 1];
                      uint64_t multiplier = 1ull;
                      switch (unit) {
                          case 'k':
                          case 'K':
                              multiplier <<= 10;
                              break;
                          case 'm':
                          case 'M':
                              multiplier <<= 20;
                              break;

Does it actually parse as B (only last letter), just hitting the default/break case and then “2GB” = “2” (bytes)?

I found it likely to be intentional and equivalent (but I didn’t check if it was actually did the same or anything, GXXX also runs and XXX), but 1.9 isn’t released, and if G is in the spec, and GB isn’t, do not rely on it to work ever… It could be changed to work before release, or not (or even changed back to spec, by accident, though unlikely).

marllos · August 23, 2022, 5:40pm

I had installed the wrong architecture. Now it’s right:
Julia Version 1.9.0-DEV.1172
Commit 18fa3835a78 (2022-08-23 13:44 UTC)

Using the --heap-size-hint=2GB or --heap-size-hint=2G option, it still shows in htop-VIRT = 9.6G instead of 2.0G as before. I also tested with and without BLAS.set_num_threads(8).

Julia also runs
julia --project=.juliadev --heap-size-hint=2any_string

Palli · August 26, 2022, 3:46pm

You may need, or want to file an issue on this.

marllos · August 26, 2022, 7:43pm

Yes, I want to, but I don’t know how to do it.

jbytecode · August 30, 2022, 7:58pm

Providing a minimal example of bloating memory usage would be great.