Feature #9196

Module#constants(false) should not use a hashtable internally

Added by charliesome (Charlie Somerville) over 6 years ago. Updated over 6 years ago.

Target version:


Module#constants always uses a hashtable to ensure that only unique constant names are returned - even when called with the inherit argument set to false.

Rails calls constants(false) heavily during boot and the use of a hashtable causes this method to show up as a hotspot (6% of boot time is spent in Module#constants).

Our app currently takes about 6.3 seconds to boot on trunk:

    6.33 real         5.20 user         1.10 sys
    6.27 real         5.17 user         1.07 sys
    6.27 real         5.17 user         1.07 sys
    6.35 real         5.25 user         1.07 sys
    6.29 real         5.18 user         1.08 sys

After applying the patch at, boot time drops to about 6 seconds:

    6.01 real         4.90 user         1.08 sys
    6.02 real         4.90 user         1.09 sys
    5.95 real         4.86 user         1.07 sys
    5.97 real         4.86 user         1.07 sys
    6.00 real         4.88 user         1.09 sys

Updated by charliesome (Charlie Somerville) over 6 years ago

  • Status changed from Open to Closed
  • % Done changed from 0 to 100

This issue was solved with changeset r43956.
Charlie, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

  • variable.c (rb_mod_constants): when calling Module#constants with inherit=false, there is no need to use a hashtable to deduplicate constant names. [Feature #9196] [ruby-core:58786]

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