fix telegram: drain both polling AND general httpx connection pools

[q3874758]

Problem

On Windows (especially with proxy software like sing-box), repeated network errors leave httpx connections in a half-closed state that still occupy pool slots. The Telegram adapter's _drain_polling_connections() method only reset the getUpdates polling request pool (_request[0]) but left the general request pool (_request[1]) untouched.

Since send_message / edit_message use the general pool (512 connections), it eventually fills up causing:
Pool timeout: All connections in the connection pool are occupied

Fix

_drain_polling_connections() now drains both polling AND general request pools. Reset runs via thread pool to avoid async event loop contention on Windows.

Testing

Gateway restarted — Telegram connects and messages send without pool timeout errors.

---

The original comment claimed the general pool was left untouched to avoid interrupting concurrent send_message/edit_message calls, but both pools are independent HTTPXRequest instances — draining one cannot affect the other.

[alt-glitch]

Complementary to #35623 (retry with fresh request fallback). This PR drains stale connections proactively; #35623 adds send-side retry when pool is already exhausted. Both address Telegram pool timeout issues. Related: #35610, #31599.

[liuhao1024]

I found a bug in the _drain_one helper that will likely cause runtime failures.

gateway/platforms/telegram.py — the new _drain_one function:

def _drain_one(name: str, req) -> None:
    try:
        loop = asyncio.get_event_loop()
    except RuntimeError:
        return
    try:
        coro = req.shutdown()
        future = loop.run_in_executor(None, asyncio.run, coro)
        future.result(timeout=5)
    ...

The problem: loop.run_in_executor(None, asyncio.run, coro) runs asyncio.run(coro) in a thread-pool worker. asyncio.run() creates a brand-new event loop in that worker thread. However, the PTB BaseRequest objects (_request[0], _request[1]) are bound to the original event loop — their internal _session (httpx AsyncClient) and transport were created on the gateway's running loop. Passing them to a different loop's asyncio.run() will either raise RuntimeError: ... is bound to a different event loop or silently create a broken session.

Suggested fix: Use asyncio.run_coroutine_threadsafe(coro, loop) instead, which schedules the coroutine on the existing loop without creating a new one:

def _drain_one(name: str, req) -> None:
    try:
        loop = asyncio.get_running_loop()
    except RuntimeError:
        return
    try:
        future = asyncio.run_coroutine_threadsafe(req.shutdown(), loop)
        future.result(timeout=5)
    except Exception:
        pass
    try:
        future = asyncio.run_coroutine_threadsafe(req.initialize(), loop)
        future.result(timeout=5)
        logger.debug("[%s] %s pool drained", self.name, name)
    except Exception:
        logger.debug("[%s] %s re-init failed (non-fatal)", self.name, name, exc_info=True)

Note: if the caller is already running on the event loop (which _drain_polling_connections is — it's an async def method), run_in_executor is the correct way to offload blocking work, but shutdown()/initialize() are async coroutines that should be scheduled on the same loop, not a new one. If the goal is truly to avoid blocking the event loop, consider await asyncio.wait_for(req.shutdown(), timeout=5) directly (since these are network-level pool resets, they're fast) or use loop.run_in_executor only for genuinely blocking I/O.

Also note that the competing PR #35623 takes a different (and correct) approach: instead of draining the existing pool, it creates a fresh one-shot Bot with its own HTTPXRequest session for the retry, bypassing pool exhaustion entirely.

[tonydwb]

Code Review Summary

Verdict: Approved ✅

What it does

Expands _drain_polling_connections() to drain BOTH the polling request pool (_request[0]) AND the general request pool (_request[1]), since either can be the source of Pool timeout: All connections in the connection pool are occupied. Uses loop.run_in_executor(None, asyncio.run, coro) to avoid blocking the async gateway event loop during shutdown()/initialize().

✅ Looks Good

• Correct diagnosis: The original code only drained the polling request pool (_request[0]), but send_message/edit_message calls through the general pool (_request[1]) can also exhaust connections
• Thread-pool safety: Wrapping async shutdown/initialize in run_in_executor avoids blocking the event loop — a subtle and correct pattern
• 5s timeout: Each drain has a 5s timeout to prevent hangs
• Graceful degradation: Both pools are drained independently; if one fails, the other still gets drained. All exceptions are caught at the inner level
• Focused change: 1 file modified, minimal diff

💡 Suggestion (non-blocking)

• The _drain_one helper catches all exceptions silently for the shutdown phase. Consider logging a debug message for shutdown failures too (currently only init failures are logged), since a failed shutdown could leave connections in a semi-closed state

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Reviewed by Hermes Agent

[tonydwb]

Code Review Summary

Verdict: Approved ✅

Reviewed Changes

• gateway/platforms/telegram.py:_drain_polling_connections — Now drains both the polling request pool AND the general request pool, using a thread-pool executor to avoid blocking the async loop.

✅ Looks Good

• Correctness: The old code only drained the polling request pool (_request[0]), but pool exhaustion can also come from the general httpx pool (_request[1]) — especially under heavy concurrent send_message/edit_message traffic. Draining both is the right fix.
• Implementation: Uses loop.run_in_executor(None, asyncio.run, coro) with future.result(timeout=5) to safely call synchronous shutdown/initialize without blocking the async event loop. This is a well-known pattern for this scenario.
• Error handling: Both shutdown and re-initialize failures are caught and logged as debug-level (non-fatal). The adapter continues regardless.
• No security concerns: No credential exposure or injection vectors.

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Reviewed by Hermes Agent

[teknium1]

Automated hermes-sweeper review: current main already fixes the Telegram general httpx pool exhaustion this PR targeted, through a safer send-side reset path.

Evidence:

• plugins/platforms/telegram/adapter.py:1029 detects PTB/httpx pool timeouts separately from ordinary TimedOut errors.
• plugins/platforms/telegram/adapter.py:1670 resets the Bot API general request pool (_request[1]) after a confirmed send-side pool timeout, with an asyncio lock around the drain.
• plugins/platforms/telegram/adapter.py:3177 calls that general-pool drain before retrying the failed send.
• plugins/platforms/telegram/adapter.py:3249 keeps exhausted-pool sends retryable instead of silently dropping them as generic timeouts.
• tests/gateway/test_telegram_thread_fallback.py:1343 covers the important behavior: a pool timeout drains _request[1] before retrying and leaves _request[0] untouched.
• The main implementation landed in 7e2ca7f68da63a29e1695b5e24901cc57e32f2ac (fix(telegram): reset send pool after pool timeouts), with related keepalive hardening in 4b7f3826c2ced4d1243b64b15785c6781f836639.

The discussion here was useful, especially the note that this PR's asyncio.run() inside an executor would put PTB request objects on the wrong event loop. The current main path avoids that shape by awaiting the request reset on the owning loop.