Use logger.isEnabledFor(logging.DEBUG) instead of logger.level <= logging.DEBUG for debug guards #1957

Summary

Throughout Socket Mode, debug logs are guarded like this:

if self.logger.level <= logging.DEBUG:
    self.logger.debug(f"... {expensive_call()} ...")

The guard exists to avoid building the message string when debug is off (the f-string argument is evaluated eagerly, before debug() can no-op it). That's a valid goal — e.g. builtin/client.py calls debug_redacted_message_string(message), and client.py calls self.message_queue.qsize() inside the message.

But logger.level is the wrong check: it's only the level explicitly set on that exact logger, defaulting to NOTSET (0). These loggers are created with logging.getLogger(__name__) and setLevel() is never called on them. So with the usual logging.basicConfig(level=logging.INFO) (which configures the root logger), logger.level stays 0, 0 <= 10 is always True, and the guard passes anyway — the expensive string still gets built. The optimization silently does nothing in the most common setup.

Suggested change

Replace:

if self.logger.level <= logging.DEBUG:

with:

if self.logger.isEnabledFor(logging.DEBUG):

isEnabledFor() uses the effective level (walking up the logger hierarchy via getEffectiveLevel()), so it correctly short-circuits when logging is configured at the root/parent — which is what the guard was meant to do.

Where the guarded message is cheap (e.g. it only interpolates an already-computed value), the guard could simply be dropped instead.

Scope

Spotted in slack_sdk/socket_mode/, but the same logger.level <= logging.DEBUG idiom appears ~88 times across ~23 files in slack_sdk/ (webhook, scim, web, audit_logs, rtm, oauth, …). isEnabledFor is currently used nowhere. Worth deciding whether to fix Socket Mode only or apply the change project-wide.