[MacPorts] #55896: lz4 @1.8.1.2_0: ar: liblz4.a: Resource temporarily unavailable

[MacPorts]

#55896: lz4 @1.8.1.2_0: ar: liblz4.a: Resource temporarily unavailable
---------------------+---------------------------
  Reporter:  kencu   |      Owner:  ryandesign
      Type:  defect  |     Status:  accepted
  Priority:  Normal  |  Milestone:
 Component:  ports   |    Version:
Resolution:          |   Keywords:  leopard tiger
      Port:  lz4     |
---------------------+---------------------------
Changes (by ryandesign):

 * cc: ryandesign (removed)
 * keywords:  powerpc => leopard tiger
 * status:  new => accepted
 * owner:   => ryandesign


Comment:

 It has now built successfully on the buildbot. The portfile hasn't changed
 and it has no dependencies.

 I believe it's a parallel build problem. The log says:

 {{{
 compiling static library
 compiling static library
 lz4.c:220: warning: ‘LZ4_write32’ defined but not used
 lz4.c:253: warning: ‘LZ4_readLE16’ defined but not used
 lz4hc.c:125: warning: ‘LZ4HC_countBack’ defined but not used
 lz4.c:220: warning: ‘LZ4_write32’ defined but not used
 lz4.c:253: warning: ‘LZ4_readLE16’ defined but not used
 lz4hc.c:125: warning: ‘LZ4HC_countBack’ defined but not used
 ar: liblz4.a: Resource temporarily unavailable
 make[1]: *** [liblz4.a] Error 1
 make[1]: Leaving directory
 `/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_archivers_lz4/lz4/work/lz4-1.8.1.2/lib'
 make: *** [liblz4.a] Error 2
 make: *** Waiting for unfinished jobs....
 }}}

 Note that the line `compiling static library`, and the three warnings
 resulting from compiling it, appear twice each. Two processes are trying
 to write the same library at the same time; one of them is prevented from
 doing so.

 I should have read the Google search results more carefully when I
 searched last week. The first hit for a search for `ar "Resource
 temporarily unavailable"` was a duplicate of #27247, which discusses the
 same error being the result of a parallel build problem on Leopard and
 earlier.

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Ticket URL: <https://trac.macports.org/ticket/55896#comment:4>
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