chained_lazy_vals

chained_lazy_vals.scala

object LazyValDeadLock extends App {                                                                                                                                                           
  println((new Z).Y)
}

class Z { 
  lazy val X = 0 
  lazy val Y = { 
    for(i <- 0 until 2 par) yield {
      println(i)
      X   
    }   
  }
}
/*
  public scala.collection.parallel.immutable.ParSeq<java.lang.Object> Y();
    Code:
      stack=5, locals=2, args_size=1
         0: aload_0       
         1: getfield      #16                 // Field bitmap$0:I
         4: iconst_2      
         5: iand          
         6: iconst_0      
         7: if_icmpne     80
        10: aload_0       
        11: dup           
        12: astore_1      
        13: monitorenter    // <------- Main thread owns the lock now
        14: aload_0       
        15: getfield      #16                 // Field bitmap$0:I
        18: iconst_2      
        19: iand          
        20: iconst_0      
        21: if_icmpne     74
        24: aload_0       
        25: getstatic     #31                 // Field scala/Predef$.MODULE$:Lscala/Predef$;
        28: iconst_0      
        29: invokevirtual #35                 // Method scala/Predef$.intWrapper:(I)Lscala/runtime/RichInt;
        32: iconst_2      
        33: invokevirtual #41                 // Method scala/runtime/RichInt.until:(I)Lscala/collection/immutable/Range;
        36: invokevirtual #47                 // Method scala/collection/immutable/Range.par:()Lscala/collection/parallel/immutable/ParRange; <------ threads are started independent from object 'Z'
        39: new           #49                 // class Z$$anonfun$Y$1
        42: dup           
        43: aload_0       
        44: invokespecial #53                 // Method Z$$anonfun$Y$1."<init>":(LZ;)V
        47: getstatic     #58                 // Field scala/collection/parallel/immutable/ParSeq$.MODULE$:Lscala/collection/parallel/immutable/ParSeq$;
        50: invokevirtual #62                 // Method scala/collection/parallel/immutable/ParSeq$.canBuildFrom:()Lscala/collection/generic/CanCombineFrom;
        53: invokeinterface #68,  3           // InterfaceMethod scala/collection/parallel/ParIterableLike.map:(Lscala/Function1;Lscala/collection/generic/CanBuildFrom;)Ljava/lang/Object;
        58: checkcast     #70                 // class scala/collection/parallel/immutable/ParSeq
        61: putfield      #72                 // Field Y:Lscala/collection/parallel/immutable/ParSeq;
        64: aload_0       
        65: aload_0       
        66: getfield      #16                 // Field bitmap$0:I
        69: iconst_2      
        70: ior           
        71: putfield      #16                 // Field bitmap$0:I
        74: getstatic     #24                 // Field scala/runtime/BoxedUnit.UNIT:Lscala/runtime/BoxedUnit;
        77: pop           
        78: aload_1       
        79: monitorexit   
        80: aload_0       
        81: getfield      #72                 // Field Y:Lscala/collection/parallel/immutable/ParSeq;
        84: areturn       
        85: aload_1       
        86: monitorexit   
        87: athrow        */