depends: make osx output deterministic #9891

1. 
   theuni commented at 9:58 PM on February 28, 2017: member

   ld64 is threaded, and uses a worker for each CPU to parse input files. But there's a bug in the parser causing dependencies to be calculated differently based on which files have already been parsed.

   As a result, builders with more CPUs are more likely to see non-determinism.

   This looks to have been fixed in a newer version of ld64, so just disable threading for now. There's no noticible slowdown.

2. MarcoFalke added this to the milestone 0.14.0 on Feb 28, 2017
3. MarcoFalke added the label Build system on Feb 28, 2017
4. theuni force-pushed on Mar 1, 2017
5. depends: make osx output deterministic

   ld64 is threaded, and uses a worker for each CPU to parse input files. But
   there's a bug in the parser causing dependencies to be calculated differently
   based on which files have already been parsed.
   
   As a result, builders with more CPUs are more likely to see non-determinism.
   
   This looks to have been fixed in a newer version of ld64, so just disable
   threading for now. There's no noticible slowdown.

   9e4d842afc
6. 
   paveljanik commented at 6:31 AM on March 1, 2017: contributor

   @theuni Brilliant investigation! Thank you!

   For more info, the unpacked code is available at https://github.com/froydnj/ld64/blob/master/src/ld/InputFiles.cpp#L716

   utACK https://github.com/bitcoin/bitcoin/pull/9891/commits/9e4d842afc67c63448cbbe30e5cea906e9c87f7e

7. 
   jonasschnelli commented at 7:18 AM on March 1, 2017: contributor

   Great, Thanks @theuni. utACK 9e4d842afc67c63448cbbe30e5cea906e9c87f7e

8. 
   laanwj commented at 9:29 AM on March 1, 2017: member

   Wow, this is a really sneaky bug. Thanks for catching it. utACK https://github.com/bitcoin/bitcoin/commit/9e4d842afc67c63448cbbe30e5cea906e9c87f7e

9. laanwj merged this on Mar 1, 2017
10. laanwj closed this on Mar 1, 2017

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11. laanwj referenced this in commit 3fabae7425 on Mar 1, 2017
12. laanwj referenced this in commit eff783a0fe on Mar 1, 2017
13. 
    achow101 commented at 1:53 PM on March 1, 2017: member

    Post merge ACK. Tested by running 50 gitian builds with this patch applied and the hashes of each build match.

14. codablock referenced this in commit 818fc1eafb on Jan 26, 2018
15. CryptoCentric referenced this in commit ed8bc3f31e on Feb 27, 2019
16. zkbot referenced this in commit a96942e809 on Dec 11, 2019
17. MarcoFalke locked this on Sep 8, 2021

Milestone
0.14.0