fix(tracing): stop set_tracing_processor_configs deadlocking on its own lock - #543

Problem

set_tracing_processor_configs() (exported from agentex.lib.core.tracing.tracing_processor_manager) never returns. TracingProcessorManager.set_processor_configs takes self.lock and then calls add_processor_config for each config, which takes the same lock again. self.lock is a threading.Lock, which is not reentrant, so the first config blocks forever:

from agentex.lib.core.tracing.tracing_processor_manager import set_tracing_processor_configs
set_tracing_processor_configs([SGPTracingProcessorConfig(...)])  # hangs

Called at ACP startup, the server never finishes booting; called before a worker starts, it never reaches worker.run(). Nothing inside the SDK calls the plural API today, which is how it went unnoticed, but it is exported next to add_tracing_processor_config.

Fix

self.lock becomes a threading.RLock. The batch still registers under one lock acquisition and the nested add_processor_config can re-enter it. add_processor_config itself is unchanged. Two-line diff.

set_processor_configs appends to the registered processors, the same as calling add_processor_config once per config. I kept that behaviour rather than making it replace the existing list; happy to change that if "set" was meant literally.

Verification

• New tests/lib/core/tracing/test_tracing_processor_manager.py registers two configs from a thread with a 5 s join.
  • Before: AssertionError: set_processor_configs blocked on the manager's own lock.
  • After: passes, and both the sync and the async processor lists hold one processor per config.
• uv run pytest -n 0 tests/lib/core/tracing/test_tracing_processor_manager.py tests/lib/core/tracing/test_span_queue.py tests/lib/core/tracing/processors: 89 passed.
• ruff check and pyright clean on both files.

Confidence Score: 4/5

The deadlock fix looks sound, but the test deadline still needs to meet the repository’s rule before merging.

Findings

1.  Test deadline has no name ▶

### Issue 1
tests/lib/core/tracing/test_tracing_processor_manager.py:undefined-27
`_finishes` uses `5.0` as an inline timeout. The repository requires magic numbers to be stored as class or instance variables with descriptive names. Name this deadline to satisfy that requirement before merging.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

The tracing processor manager now uses a lock that its own thread can enter again, so batch registration can finish. New tests check batch registration and the single-config path.

• Batch registration adds matching sync and async processors for each config.
• A timed thread check confirms the batch call completes.

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