search_bot conflated MAXTHREADS into two jobs at once - how many chunk files to
read (files 0..MAXTHREADS-1) AND how many producer sentinels to wait for - so
the two had to match exactly. Set too low it silently skipped trailing chunks;
set too high (or with any chunk missing/unreadable) a producer crashed before
emitting its sentinel, the consumers' count never reached the threshold, and
search_for_doi hung on join() forever. The idle-timeout failsafe that was meant
to break a starved consumer was dead code: `if empty_counter > 5: ... elif
empty_counter > 10: break` - >10 implies >5, so the elif never ran.
Fix, three layers:
* auto-discover the chunk files present (discover_chunk_files: <n>_chunk.txt in
numeric order) instead of range(0, MAXTHREADS). All files are read regardless
of count, and no producer is ever pointed at a missing file;
* the sentinel threshold is now the number of producers actually started, so it
can't drift from what's emitted;
* producers emit their sentinel in a finally, so even a crash (missing/unreadable
chunk) can't starve the count; and the idle backstop is reordered so it can
actually fire (>EMPTY_LIMIT seconds) as a last resort.
MAXTHREADS is deprecated and unused (kept only so old env files don't break);
docs/env updated to say chunk files are auto-discovered.
For the reported case (MAXTHREADS=40, files 0..43): before, files 40-43 were
silently never searched, and any run that referenced a missing chunk hung
forever. After, all 44 are searched and it always terminates.
Verified in a pytest-only venv (tests/unit/test_search_bot.py): DOI in a
trailing chunk is found; an unreadable chunk still terminates; empty dir returns
at once; discovery is numeric-sorted. Full unit job 27 passed.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
