[package cl21.process]..;
; caught ERROR:
;   READ error during COMPILE-FILE:
;
;     Lock on package SB-IMPL violated when interning WAITPID while in package
;     CL21.PROCESS.
;   See also:
;     The SBCL Manual, Node "Package Locks"
;
;     (in form starting at line: 172, column: 0, position: 5386)

debugger invoked on a UIOP/LISP-BUILD:COMPILE-FILE-ERROR in thread
#<THREAD "main thread" RUNNING {10029F3BE3}>:
  COMPILE-FILE-ERROR while
  compiling #<CL-SOURCE-FILE "cl21" "src" "stdlib" "process">

Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [RETRY                        ] Retry
                                     compiling #<CL-SOURCE-FILE "cl21" "src" "stdlib" "process">.
  1: [ACCEPT                       ] Continue, treating
                                     compiling #<CL-SOURCE-FILE "cl21" "src" "stdlib" "process">
                                     as having been successful.
  2:                                 Retry ASDF operation.
  3: [CLEAR-CONFIGURATION-AND-RETRY] Retry ASDF operation after resetting the
                                     configuration.
  4: [ABORT                        ] Give up on "cl21"
  5:                                 Exit debugger, returning to top level.