# Addprocs() does not work

**URL:** <https://discourse.julialang.org/t/addprocs-does-not-work/58211>\
**Category:** General Usage\
**Created:** [March 30, 2021, 9:38am UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211 "2021-03-30T09:38:26Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![mariok90](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mariok90/32/7076_2.png) [@mariok90](https://discourse.julialang.org/u/mariok90)\
**Post date:** [March 30, 2021, 9:38am UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211/1 "2021-03-30T09:38:26Z")

</div>

When I use `addprocs()` julia crashes with that error message:

```julia
julia> using Distributed

julia> workers()
1-element Array{Int64,1}:
 1

julia> addprocs()
16-element Array{Int64,1}:
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17

julia>
      From worker 16: Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks.
      From worker 5:
      From worker 5: Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks.
      From worker 5: Exception: UNKNOWN at 0x7fff4ba9d759 -- unknown function (ip: 00007fff4ba9d759)
      From worker 5: in expression starting at none:0
      From worker 5: unknown function (ip: 00007fff4ba9d759)
      From worker 5: unknown function (ip: 000000006144d620)
      From worker 5: unknown function (ip: 000000006fd436c2)
      From worker 5: unknown function (ip: 000000006fd42bbf)
      From worker 5: unknown function (ip: 000000000437d668)
      From worker 5: unknown function (ip: 0000000002c2af7c)
      From worker 5: unknown function (ip: 0000000002c2da64)
      From worker 5: unknown function (ip: 0000000002c22a37)
      From worker 5: unknown function (ip: 0000000002cc5f6a)
      From worker 5: unknown function (ip: 0000000002cca020)
      From worker 5: unknown function (ip: 0000000002ccbb15)
      From worker 5: unknown function (ip: 0000000003cbe060)
      From worker 5: unknown function (ip: 000000000292c042)
      From worker 5: unknown function (ip: 00000000027ae389)
      From worker 5: unknown function (ip: 00000000027ae472)
      From worker 5: unknown function (ip: 00000000027ad61f)
      From worker 16: Exception: UNKNOWN at 0x7fff4ba9d759 -- unknown function (ip: 00007fff4ba9d759)
      From worker 16: in expression starting at none:0
      From worker 16: unknown function (ip: 00007fff4ba9d759)
      From worker 16: Unwind_RaiseException at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libgcc_s_seh-1.dll (unknown line)
      From worker 16: unknown function (ip: 000000006fd436c2)
      From worker 16: unknown function (ip: 000000006fd42bbf)
      From worker 16: unknown function (ip: 000000000437d668)
      From worker 16: unknown function (ip: 0000000002c2af7c)
      From worker 16: unknown function (ip: 0000000002c2da64)
      From worker 16: unknown function (ip: 0000000002c22a37)
      From worker 16: unknown function (ip: 0000000002cc5f6a)
      From worker 16: unknown function (ip: 0000000002cca020)
      From worker 16: unknown function (ip: 0000000002ccbb15)
Worker 16 terminated. From worker 16: unknown function (ip: 0000000003cbe060)

      From worker 16: unknown function (ip: 000000000292c042)Worker 5 terminated.

      From worker 16: unknown function (ip: 00000000027ae389)
      From worker 16: unknown function (ip: 00000000027ae472)
      From worker 16: unknown function (ip: 00000000027ad61f)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_extern_c at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jl_extern_c at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jl_generate_fptr at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_get_unspecialized at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_apply_generic at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: unknown function (ip: 000000000992972a)
      From worker 16: jl_f_tuple at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_f__apply_latest at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: unknown function (ip: 0000000009ee7c44)
      From worker 16: unknown function (ip: 0000000009936251)
      From worker 16: unknown function (ip: 000000000993658c)
      From worker 16: unknown function (ip: 00000000099365ae)
      From worker 16: jl_finish_task at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: Allocations: 829967 (Pool: 829728; Big: 239); GC: 1
      From worker 16:
      From worker 16: Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks.
      From worker 16: Exception: EXCEPTION_ACCESS_VIOLATION at 0x2977418 -- unknown function (ip: 0000000002977418)
      From worker 16: in expression starting at none:0
      From worker 16: unknown function (ip: 0000000002977418)
      From worker 16: unknown function (ip: 000000000297c5f1)
      From worker 16: unknown function (ip: 000000000297db37)
      From worker 16: unknown function (ip: 0000000002973d27)
      From worker 16: unknown function (ip: 000000000297d35d)
      From worker 16: unknown function (ip: 000000000292c042)
      From worker 16: unknown function (ip: 00000000027ae389)
      From worker 16: unknown function (ip: 00000000027ae472)
      From worker 16: unknown function (ip: 00000000027ad61f)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_extern_c at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jl_extern_c at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jl_generate_fptr at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_get_unspecialized at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_apply_generic at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jlbacktrace at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jlbacktrace at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jlbacktrace at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jl_atexit_hook at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_exit at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_exception_handler at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: _julia_personality at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: unknown function (ip: 00007fff4e351f6e)
      From worker 16: unknown function (ip: 00007fff4e301453)
      From worker 16: unknown function (ip: 00007fff4e3011a4)
      From worker 16: unknown function (ip: 00007fff4ba9d758)
      From worker 16: Unwind_RaiseException at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libgcc_s_seh-1.dll (unknown line)
      From worker 16: unknown function (ip: 000000006fd436c2)
      From worker 16: unknown function (ip: 000000006fd42bbf)
      From worker 16: unknown function (ip: 000000000437d668)
      From worker 16: unknown function (ip: 0000000002c2af7c)
      From worker 16: unknown function (ip: 0000000002c2da64)
      From worker 16: unknown function (ip: 0000000002c22a37)
      From worker 16: unknown function (ip: 0000000002cc5f6a)
      From worker 16: unknown function (ip: 0000000002cca020)
      From worker 16: unknown function (ip: 0000000002ccbb15)
      From worker 16: unknown function (ip: 0000000003cbe060)
      From worker 16: unknown function (ip: 000000000292c042)
      From worker 16: unknown function (ip: 00000000027ae389)
      From worker 16: unknown function (ip: 00000000027ae472)
      From worker 16: unknown function (ip: 00000000027ad61f)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_dump_compiles at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_extern_c at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jl_extern_c at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line) From worker 16: jl_generate_fptr at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_get_unspecialized at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_apply_generic at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: unknown function (ip: 000000000992972a)
      From worker 16: jl_f_tuple at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: jl_f__apply_latest at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: unknown function (ip: 0000000009ee7c44)
      From worker 16: unknown function (ip: 0000000009936251)
      From worker 16: unknown function (ip: 000000000993658c)
      From worker 16: unknown function (ip: 00000000099365ae)
      From worker 16: jl_finish_task at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\bin\libjulia.dll (unknown line)
      From worker 16: Allocations: 829967 (Pool: 829728; Big: 239); GC: 1
      From worker 15: Internal error: encountered unexpected error in runtime:
      From worker 15: reset_page at /cygdrive/c/buildbot/worker/package_win64/build/src\gc.c:1093 [inlined]
      From worker 15: add_page at /cygdrive/c/buildbot/worker/package_win64/build/src\gc.c:1125
      From worker 15: jl_gc_pool_alloc at /cygdrive/c/buildbot/worker/package_win64/build/src\gc.c:1178 [inlined]
      From worker 15: jl_gc_alloc_ at /cygdrive/c/buildbot/worker/package_win64/build/src\julia_internal.h:277 [inlined]
      From worker 15: jl_gc_alloc at /cygdrive/c/buildbot/worker/package_win64/build/src\gc.c:3150
      From worker 15: jl_gc_alloc_buf at /cygdrive/c/buildbot/worker/package_win64/build/src\julia_internal.h:304 [inlined]
      From worker 15: array_resize_buffer at /cygdrive/c/buildbot/worker/package_win64/build/src\array.c:686
      From worker 15: jl_array_grow_at_end at /cygdrive/c/buildbot/worker/package_win64/build/src\array.c:875 [inlined]
      From worker 15: jl_array_grow_end at /cygdrive/c/buildbot/worker/package_win64/build/src\array.c:939
      From worker 15: _growend! at .\array.jl:892 [inlined]
      From worker 15: resize! at .\array.jl:1085 [inlined]
      From worker 15: resize! at .\compiler/ssair\ir.jl:992
      From worker 15: iterate at .\compiler/ssair\ir.jl:1101
      From worker 15: ir_inline_item! at .\compiler/ssair\inlining.jl:396
      From worker 15: batch_inline! at .\compiler/ssair\inlining.jl:552
      From worker 15: ssa_inlining_pass! at .\compiler/ssair\inlining.jl:77 [inlined]
      From worker 15: run_passes at .\compiler/ssair\driver.jl:138
      From worker 15: optimize at .\compiler\optimize.jl:174
      From worker 15: typeinf at .\compiler\typeinfer.jl:33
      From worker 15: typeinf_ext at .\compiler\typeinfer.jl:570
      From worker 15: typeinf_ext at .\compiler\typeinfer.jl:601
      From worker 15: jfptr_typeinf_ext_20437.clone_1 at C:\Users\mario\AppData\Local\Programs\Julia 1.5.3\lib\julia\sys.dll (unknown line)
      From worker 15: _jl_invoke at /cygdrive/c/buildbot/worker/package_win64/build/src\gf.c:2214 [inlined]
      From worker 15: jl_apply_generic at /cygdrive/c/buildbot/worker/package_win64/build/src\gf.c:2398 [inlined]
      From worker 15: jl_apply at /cygdrive/c/buildbot/worker/package_win64/build/src\julia.h:1690 [inlined]
      From worker 15: jl_type_infer at /cygdrive/c/buildbot/worker/package_win64/build/src\gf.c:296
      From worker 15: jl_generate_fptr at /cygdrive/c/buildbot/worker/package_win64/build/src\jitlayers.cpp:290
      From worker 15: jl_compile_method_internal at /cygdrive/c/buildbot/worker/package_win64/build/src\gf.c:1964
      From worker 15: jl_compile_method_internal at /cygdrive/c/buildbot/worker/package_win64/build/src\gf.c:1931 [inlined]
      From worker 15: _jl_invoke at /cygdrive/c/buildbot/worker/package_win64/build/src\gf.c:2224 [inlined]
      From worker 15: jl_apply_generic at /cygdrive/c/buildbot/worker/package_win64/build/src\gf.c:2398
      From worker 15: jl_apply at /cygdrive/c/buildbot/worker/package_win64/build/src\julia.h:1690 [inlined]
      From worker 15: do_apply at /cygdrive/c/buildbot/worker/package_win64/build/src\builtins.c:655
      From worker 15: #114 at C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Distributed\src\process_messages.jl:315
      From worker 15: run_work_thunk at C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Distributed\src\process_messages.jl:79
      From worker 15: #113 at .\task.jl:356
      From worker 15: unknown function (ip: 000000001965dbe3)
      From worker 15: jl_apply at /cygdrive/c/buildbot/worker/package_win64/build/src\julia.h:1690 [inlined]
      From worker 15: start_task at /cygdrive/c/buildbot/worker/package_win64/build/src\task.c:705
      From worker 15: ReadOnlyMemoryError()

```

It does not matter if I use version 1.6 or 1.5.3. Any idea how to fix this?

---

<div class="post-metadata">

**Author:** ![kaslusimoes](https://avatars.discourse-cdn.com/v4/letter/k/b19c9b/32.png) [@kaslusimoes](https://discourse.julialang.org/u/kaslusimoes)\
**Post date:** [March 30, 2021, 12:39pm UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211/2 "2021-03-30T12:39:53Z")

</div>

Hi,

I’m definitely not someone knowledgeable in this, but a couple of questions that might give relevant information to the clever guys around here

- Does that also happen if you run `addprocs(1)`?
- What is the output for `Sys.CPU_THREADS`?
- Where are you running this? Which machine, which OS? Maybe give us the output of `versioninfo()`

---

<div class="post-metadata">

**Author:** ![mariok90](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mariok90/32/7076_2.png) [@mariok90](https://discourse.julialang.org/u/mariok90)\
**Post date:** [March 30, 2021, 12:51pm UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211/3 "2021-03-30T12:51:19Z")

</div>

Thanks for the reply. `versioninfo()` yields:

```julia
Julia Version 1.5.3
Commit 788b2c77c1 (2020-11-09 13:37 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: Intel(R) Core(TM) i9-9900KF CPU @ 3.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-9.0.1 (ORCJIT, skylake)

```

Strangely, `addprocs(1)` also works without an error.

---

<div class="post-metadata">

**Author:** ![kaslusimoes](https://avatars.discourse-cdn.com/v4/letter/k/b19c9b/32.png) [@kaslusimoes](https://discourse.julialang.org/u/kaslusimoes)\
**Post date:** [March 30, 2021, 12:54pm UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211/4 "2021-03-30T12:54:17Z")

</div>

Have you checked `Sys.CPU_THREADS`? On the documentation it says that calling `addprocs` without argument uses that value as a default, and considering that `addprocs(1)` works I’m thinking if maybe you’re adding more procs than you can (not sure if there’s such a thing as “can” here, though, just a guess of mine)

---

<div class="post-metadata">

**Author:** ![mariok90](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mariok90/32/7076_2.png) [@mariok90](https://discourse.julialang.org/u/mariok90)\
**Post date:** [March 30, 2021, 1:07pm UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211/5 "2021-03-30T13:07:05Z")

</div>

> [@kaslusimoes](#):
>
> `Sys.CPU_THREADS`

```julia
julia> Sys.CPU_THREADS
16

```

`addprocs()` used to work some time ago at least…

---

<div class="post-metadata">

**Author:** ![kaslusimoes](https://avatars.discourse-cdn.com/v4/letter/k/b19c9b/32.png) [@kaslusimoes](https://discourse.julialang.org/u/kaslusimoes)\
**Post date:** [March 30, 2021, 1:18pm UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211/6 "2021-03-30T13:18:41Z")

</div>

> [@mariok90](#):
>
> `addprocs()` used to work some time ago at least…

I see… Well, my guess was a long-shot anyway. Not sure what the problem might be, sorry 😕 I tried the same here but without error.

Hopefully someone else will pop in soon and help you, but perhaps in the meantime you can just find the upper bound of `addprocs(x)` that you can use without Julia crashing 🙂

---

<div class="post-metadata">

**Author:** ![mariok90](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mariok90/32/7076_2.png) [@mariok90](https://discourse.julialang.org/u/mariok90)\
**Post date:** [March 30, 2021, 1:25pm UTC](https://discourse.julialang.org/t/addprocs-does-not-work/58211/7 "2021-03-30T13:25:37Z")

</div>

I just rebooted my computer and now it works again. Should have done that sooner… Thanks for your effort anyway! It was probably some Windows related issue.