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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:
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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.
Example
The following structure shows how the stack may look like (notice that in order to save space, the stack is created from left to right). This structure allows to reconstruct, that M1 called M2 and afterwards called M3.
M1 start | M2 start | M2 end | M3 start | M3 end | M1 end |
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
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