...
- Each invocation of a method checks if an invocation sequence is currently active
- The staging area builds up a stack of all methods that are invoked within one "thread"
- This stack must be unique for each thread identification
- The data is sent to the CMR. Based on the JVM identification, the ... the platform identification and the thread identification, the CMR can extend its stack of the methods of one invocation by adding the received stack to it. If no information is currently available, the CMR must assume that this was a new invocation.
Inner-Thread
Invocations within one thread are saved as a stack that is unique per thread identification.
The invocation of an instrumented method within an invocation sequence will create two different information objects:
- one at the start of the method and (method~start~)
- one at the end of the method (method~end~)
Additional identification of the methods are not necessary as the invocations within the thread are always synchronous and thus the stack of the invocations will easily allow to reconstruct the invocation sequence.
Inter-Thread
Braindump
- Each thread has a unique number (per JVM) automatically assigned
- But threads can and - in fact are - reused. For example thread pools do not instantiate new threads, but instead pass different Runnable instances to the existing threads. Each different runnable is itself a different functionality. Thus the thread ID cannot be safely used for identification
- To build up an invocation sequence, each invoked method must know the method that was invoked before it
- Innerthread communication can simply make use of the ThreadLocal pattern and build a stack of the concrete methods being called
- Interthread and inter JVM communication has to connect the stacks of the involved threads. This can be done by an invocation identifier that is passed from the caller to the callee.
- Invocation identifier must also include the method identification that invoked this call
- Continuous sending of information
- Each method needs to have a thread-wide identification (stored within the stack)
- Each invocation of a method must refer to the parent invocation
- CMR server can match its current call tree with the information sent by the agent. Based on the invocation identification it will find the correct sequence. it will use the method identification to complete the tree
...