Difference between revisions of "Java Team4 Benchmark1"

Revision as of 09:57, 26 May 2016

This benchmark aims at measuring the performance of tracking the behaviour of a large number of communicating entities. These entities are represented by objects, but they are is asumed to be external to the benchmark program. A scenario where this is applicable is a coordinator node in a large networked cluster spanning several machines. In such a scenario it should be avoided to replicate the behaviour of the external nodes for ther purpose of runtime verification, as this defeats the purpose of distributing work in a cluster.

Category: Concurrency

Benchmark Data

Specification Information

The benchmark maintains a tree data structure consisting of two different type of objects: inner nodes and leaf nodes. There is a single root node of type InnerNode. Each InnerNode has an ordered list of InnerNode children and an ordered list of LeafNode children. The object graph is an actual tree, i.e. there are no cycles or multiple references to the same object.

The structure of the tree can be changed dynamically by adding or removing nodes of either type.

The specification considers 6 different abstract events:

• create(n)
• send(i)
• sendCritical(i)
• reset(i)
• process(l)
• invalidate(n)

Where i, l and n are a sequence of object IDs, which form a consecutive path starting from the root node to an inner, a leaf or an arbitrary node respectively. It can be assumed that all occuring events are a valid path in the tree and end in a node of the correct type for the event.

Informally every leaf node has an external buffer that can hold up to one message. Whenever a send operation is performed on an inner node, all descendant leaf nodes which currently have an empty buffer store this message in their buffer. Whenever a sendCritical operation is performed the same behaviour as for a send operation is performed, but the specification requires that all descendant leaf nodes have an empty buffer. A reset operation on an inner node clears the buffers of all descendant leaf nodes. A process operation on a leaf node, clears the buffer of the leaf node, but the specification requires that the buffer contains a message for this operation to be valid. Finally both types of nodes are invalidated before they are removed from the tree structure. After an invalidate operation is performed on a node, none of the previously described operations may be performed on the node or any of its descendant nodes.

The formal specification is given in the form of a symbolic monitor for leaf nodes and a symbolic monitor for inner nodes:

• Leaf Nodes:
  • State space Q = {0,1,2,3,4}
  • Initial state: 0
  • Quantification: ∀l : LeafNodes
  • Transitions:
    • δ(0, create(l)) = 1
    • δ(0, otherwise) = 0
    • δ(1, ∃m : send(m) ∧ prefix(m, l)) = 2
    • δ(1, ∃m : sendCritical(m) ∧ prefix(m, l)) = 2
    • δ(1, ∃m : reset(m) ∧ prefix(m, l)) = 1
    • δ(1, ∃m : invalidate(m) ∧ prefix(m, l)) = 3
    • δ(1, process(l)) = 4
    • δ(1, otherwise) = 1
    • δ(2, ∃m : send(m) ∧ prefix(m, l)) = 2
    • δ(2, ∃m : sendCritical(m) ∧ prefix(m, l)) = 4
    • δ(2, ∃m : reset(m) ∧ prefix(m, l)) = 1
    • δ(2, ∃m : invalidate(m) ∧ prefix(m, l)) = 3
    • δ(2, process(l)) = 1
    • δ(2, otherwise) = 2
    • δ(3, process(l)) = 4
    • δ(3, otherwise) = 3
    • δ(4, true) = 4
  • Accepting states (with output ⊤) F = {0,1,2,3}
• Inner Nodes:
  • State space Q = {0,1,2,3}
  • Initial state: 0
  • Quantification: ∀i : InnerNodes
  • Transitions:
    • δ(0, create(i)) = 1
    • δ(0, otherwise) = 0
    • δ(1, ∃m : invalidate(m) ∧ prefix(m, i)) = 2
    • δ(1, otherwise) = 1
    • δ(2, send(i)) = 3
    • δ(2, sendCritical(i)) = 3
    • δ(2, reset(i)) = 3
    • δ(3, true) = 3
  • Accepting states (with output ⊤) F = {0,1,2}

The prefix(m, n) is a reflexive relation that is true if m is a prefix of (or equal to) n.

Instrumentation Information

The concrete events are specified as AspectJ pointcuts, and are also specified in the file InstrumentationAspect.aj.

The concrete events only refer to a single object while the abstract events require a sequence of object IDs that represents the path from the root node. To allow the runtime verification to keep track of the required paths, the two concrete events for the create(n) event contain the parent node:

   public pointcut newInnerChild(InnerNode node, int i) :
       call(* InnerNode.addInnerNode(int)) && args(i) && target(node);

   public pointcut newLeafChild(InnerNode node, int i) :
       call(* InnerNode.addLeafNode(int)) && args(i) && target(node);

They have the parent node as a paremeter and the child node, which is the n in create(n) as return value.

As a special case an abstract create([r]) event occurs first, when one of the two concrete abstract events occurs with a parent object r that is not yet a child of any other object.

The abstract events send(i), sendCritical(i), rest(i) and process(l) correspond to the concrete events given by:

   public pointcut send(InnerNode node) :
       call(* InnerNode.send()) && target(node);

   public pointcut sendCritical(InnerNode node) :
       call(* InnerNode.sendCritical()) && target(node);

   public pointcut reset(InnerNode node) :
       call(* InnerNode.reset()) && target(node);

   public pointcut process(LeafNode node) :
       call(* LeafNode.process()) && target(node);

As mentioned before, the concrete events contain only a single object, which has to be augmented by the path from the root to generate the corresponding abstract event.

The invalidate(n) event is given by two different concrete events, one for inner nodes and one for leaf nodes:

   public pointcut invalidateInner(InnerNode node, int i) :
       call(* InnerNode.removeInnerNode(int)) && args(i) && target(node);

   public pointcut invalidateLeaf(InnerNode node, int i) :
       call(* InnerNode.removeLeafNode(int)) && args(i) && target(node);

In this case, due to the chosen API, the concrete events do not contain the target node, but its parent node. The InnerNode.getInnerNode(int index) and InnerNode.getLeafNode(int index) methods can be used to get the target node in the instrumentation. Again the path from the root has to be augmented to generate the corresponding abstract event.

Program Information

Location: Java_track/Mufin/Benchmark3

• The number of times the (concrete) events should be observed in the program:
  • RunGood
    • newInnerChild * 1117488
    • newLeafChild * 4053676
    • send * 2146847
    • sendCritical * 713656
    • reset * 704834
    • process * 2820272
    • invalidateInner * 1249
    • invalidateLeaf * 1724
  • RunProcessAfterRemove
    • newInnerChild * 1094892
    • newLeafChild * 3964204
    • send * 2089862
    • sendCritical * 693990
    • reset * 683744
    • process * 2751055
    • invalidateInner * 1234
    • invalidateLeaf * 1630
  • RunSendAfterRemove
    • newInnerChild * 1262283
    • newLeafChild * 4478350
    • send * 2066708
    • sendCritical * 688434
    • reset * 675714
    • process * 2699530
    • invalidateInner * 1260
    • invalidateLeaf * 1674
  • RunSendCriticalAfterRemove
    • newInnerChild * 1336456
    • newLeafChild * 4721335
    • send * 2102046
    • sendCritical * 699816
    • reset * 689716
    • process * 2750065
    • invalidateInner * 1199
    • invalidateLeaf * 1689
  • RunResetAfterRemove
    • newInnerChild * 1059894
    • newLeafChild * 3764131
    • send * 2117672
    • sendCritical * 702734
    • reset * 690549
    • process * 2781575
    • invalidateInner * 1234
    • invalidateLeaf * 1717
  • RunEmptyProcess
    • newInnerChild * 1050737
    • newLeafChild * 3677949
    • send * 2166524
    • sendCritical * 721724
    • reset * 711998
    • process * 2830834
    • invalidateInner * 1169
    • invalidateLeaf * 1512
  • RunFullSendCritical
    • newInnerChild * 1208958
    • newLeafChild * 4360356
    • send * 1996323
    • sendCritical * 665400
    • reset * 654291
    • process * 2601753
    • invalidateInner * 1282
    • invalidateLeaf * 1796

• Verdict:
  • property is violated

Example Traces

Capital letters represent object IDs of inner nodes, numbers represent object IDs of leaf nodes.

Valid:

• create([A]) create([A, 0]) create([A, 1]) sendCritical([A]) send([A]) process([A, 0])
• create([A]) create([A, 0]) create([A, B]) create([A, B, 1]) send([A, 0]) reset([A]) send([A]) process([A, B, 1])
• create([A]) create([A, B]) create([A, B, 0]), create([A, B, 1]) send([A, B]) invalidate([A, B, 0]) process([A, B, 1]) sendCritical([A])

Invalid:

• create([A]) create([A, B]) create([A, B, 0]) invalidate([A, B]) process([A, B, 0])
• create([A]) create([A, B]) create([A, B, C]) invalidate([A, B]) send([A, B, C])
• create([A]) create([A, B]) create([A, B, 1]) invalidate([A, B]) sendCritical([A, B])
• create([A]) create([A, B]) create([A, B, C]) invalidate([A, B, C]) reset([A, B, C])
• create([A]) create([A, B]) create([A, B, 0]) create([A, C]) send([A, C]) process([A, B, 0])
• create([A]) create([A, 0]) send([A]) sendCritical([A])

Comments

Clarification Requests