.

tox.ini

 # wendelin.core | tox setup
 [tox]
-envlist = py27-{ZODB3,ZODB4,ZODB5}-{zblk0,zblk1}-{fs,zeo,neo}-{numpy113,numpy114}-{!wcfs,wcfs}, {py35,py36}-{ZODB4,ZODB5}-{zblk0,zblk1}-{fs,zeo}-{numpy113,numpy114}-{!wcfs,wcfs}
+envlist = py27-{ZODB3,ZODB4,ZODB5}-{zblk0,zblk1}-{fs,zeo,neo}-{numpy113,numpy114}-{!wcfs,wcfs:1,wcfs}, {py35,py36}-{ZODB4,ZODB5}-{zblk0,zblk1}-{fs,zeo}-{numpy113,numpy114}-{!wcfs,wcfs:1,wcfs}
 # (NOTE ZODB3 does not work on python3)
 # (NOTE NEO does not work on python3 at all)
 # (XXX ZODB5-*-neo are currently failing)
 
-# TODO wcfs ncpu=1, ncpu>1
-
 [testenv]
 deps    =
     # why tox does not get it from extras_require['test'] ?
@@ -49,6 +47,10 @@ setenv =
     !wcfs:  WENDELIN_CORE_VIRTMEM=rw:uvmm
     wcfs:   WENDELIN_CORE_VIRTMEM=r:wcfs+w:uvmm
 
+    # some bugs are only likely to trigger when there is only 1 main OS thread in wcfs
+    wcfs:1: WENDELIN_CORE_VIRTMEM=r:wcfs+w:uvmm
+    wcfs:1: GOMAXPROCS=1
+
 commands= {envpython} setup.py test
 # XXX setenv = TMPDIR = ... ?  (so that /tmp is not on tmpfs and we don't run out of memory on bench)
 # + {envpython} setup.py bench  (?)