(defmacro without-gcing (&body body)
#!+sb-doc
- "Executes the forms in the body without doing a garbage
-collection. It inhibits both automatically and explicitly triggered
-gcs. Finally, upon leaving the BODY if gc is not inhibited it runs the
-pending gc. Similarly, if gc is triggered in another thread then it
-waits until gc is enabled in this thread."
+ "Executes the forms in the body without doing a garbage collection. It
+inhibits both automatically and explicitly triggered collections. Finally,
+upon leaving the BODY if gc is not inhibited it runs the pending gc.
+Similarly, if gc is triggered in another thread then it waits until gc is
+enabled in this thread.
+
+Implies SB-SYS:WITHOUT-INTERRUPTS for BODY, and causes any nested
+SB-SYS:WITH-INTERRUPTS to signal a warning during execution of the BODY.
+
+Should be used with great care, and not at all in multithreaded application
+code: Any locks that are ever acquired while GC is inhibited need to be always
+held with GC inhibited to prevent deadlocks: if T1 holds the lock and is
+stopped for GC while T2 is waiting for the lock inside WITHOUT-GCING the
+system will be deadlocked. Since SBCL does not currently document its internal
+locks, application code can never be certain that this invariant is
+maintained."
`(unwind-protect
- (let ((*gc-inhibit* t))
+ (let* ((*interrupts-enabled* nil)
+ (*gc-inhibit* t))
,@body)
- ;; the test is racy, but it can err only on the overeager side
- (sb!kernel::maybe-handle-pending-gc)))
+ (when (or (and *interrupts-enabled* *interrupt-pending*)
+ (and (not *gc-inhibit*)
+ (or *gc-pending* #!+sb-thread *stop-for-gc-pending*)))
+ (sb!unix::receive-pending-interrupt))))
\f
;;; EOF-OR-LOSE is a useful macro that handles EOF.