set the proper number of minimum threads this time

common/src/main/scala/org/specs2/concurrent/ExecutionEnv.scala

@@ -57,7 +57,7 @@ object ExecutionEnv {
 
   /**
    * the number of executors is set from the arguments.threadsNb value which is
-   * Runtime.getRuntime.availableProcessors by default
+   * min(Runtime.getRuntime.availableProcessors, 4) by default
    */
   def executor(threadsNb: Int, name: String): ExecutorService =
     Executors.newFixedThreadPool(threadsNb, NamedThreadFactory("specs2.fixed."+name))

common/src/main/scala/org/specs2/control/eff/ExecutorServices.scala

@@ -35,7 +35,7 @@ case class ExecutorServices(executorServiceEval:   Evaluated[ExecutorService],
 
 object ExecutorServices {
 
-  lazy val threadsNb = math.min(Runtime.getRuntime.availableProcessors, 4)
+  lazy val threadsNb = math.max(Runtime.getRuntime.availableProcessors, 4)
 
   def create(implicit es: ExecutorService, s: ScheduledExecutorService): ExecutorServices =
     fromExecutorServices(es, s)

notes/3.9.4.markdown

@@ -0,0 +1,11 @@
+Maintenance version (3.9.3 was incorrect)
+
+## Improvements
+
+ * **core** when checking for the equality of 2 sets of lines only run the edit distance difference on them if they are different.
+ this improves build times
+
+## Fixes
+
+ * **core** set the minimum number of execution threads to 4 to avoid possible deadlocks on single core machines (cf some CI environments)
+ * **core** use the "user" execution environment to execute examples instead of specs2 own execution environment

version.sbt

@@ -1 +1 @@
-version in ThisBuild := "3.9.3"
+version in ThisBuild := "3.9.4"