After submitting the topology using the Streaming client shell command in the Fusionlnsight HD system, use Storm and UI to check and find that the topology has not processed data for a long time. What are the reasons?

A submitted Storm topology in a FusionInsight HD system may fail to process data for several critical reasons. Firstly, if all supervisor worker slots are occupied by other running topologies, the Nimbus scheduler cannot allocate the necessary resources to start the new topology's workers, leaving it in a pending state (B). Secondly, a fatal logic error within the user's code (e.g., in a spout or bolt's initialization) can cause worker processes to crash or hang immediately after startup, preventing any data processing (C). Lastly, a highly complex or concurrent topology might exceed the supervisor.worker.start.timeout.secs parameter during its initialization phase. This causes the supervisor to terminate the worker, resulting in a continuous restart loop where the topology never becomes fully operational (A).

D. Slow processing speed due to a large data volume is a performance bottleneck, not a complete failure to process data as implied by the question.

1. Regarding Resource Exhaustion (Slots): The Apache Storm architecture, which FusionInsight HD utilizes, relies on supervisors providing worker slots. If none are available, a topology cannot start. The official documentation states, "Each supervisor node has a configured number of slots... Each slot is a port for running a worker."

Source: Apache Storm Documentation, "Concepts". (This is a foundational concept of Storm architecture).

2. Regarding Startup Timeouts: Supervisors monitor worker startup and will terminate processes that fail to initialize within a specific timeframe. This is a configurable parameter.

Source: Apache Storm Documentation, "Configuration". The parameter supervisor.worker.start.timeout.secs is defined as the "Maximum number of seconds a worker has to start. If a worker fails to start within this time, the supervisor will try to restart it." This directly supports reason A.

3. Regarding Logic Errors: Application-level errors are a primary cause of topology failure. Huawei's official documentation for FusionInsight HD troubleshooting emphasizes checking worker logs for exceptions.

Source: Huawei FusionInsight HD 6.5.1 Troubleshooting Guide, Document Issue 13, Section "Storm Faults", Subsection "A Task Is Abnormal". The guide instructs users to "Check the worker log of the task to view the exception stack information and locate the fault based on the code logic." This directly supports reason C.

4. Regarding Supervisor Slot Allocation: The process of topology submission and worker allocation is a core function. If slots are unavailable, the topology remains inactive.

Source: Huawei FusionInsight HD 6.5.1 Administrator Guide, Document Issue 13, Section "Managing Storm", Subsection "Querying the Storm Cluster Status". The guide explains that the Storm UI shows resource usage, including the number of used and free slots, which is a key indicator for diagnosing allocation failures (reason B).