cs: avoid thread misuse during GC

A collection can only invoke certain callabcks (e.g., for DrRacket's
GC icon) when the collection is performed in the main thread. Also,
delay posting GC logging events to receivers that cannot work at
interrupt time.

racket/src/cs/main.sps

@@ -416,18 +416,20 @@
                        (and (not minor?)
                             (log-level? root-logger 'debug 'GC:major)))
                (let ([delta (- pre-allocated post-allocated)])
-                 (log-message root-logger 'debug (if debug-GC? 'GC 'GC:major)
+                 (log-message* root-logger 'debug (if debug-GC? 'GC 'GC:major)
-                              (chez:format "GC: 0:~a~a @ ~a(~a); free ~a(~a) ~ams @ ~a"
+                               (chez:format "GC: 0:~a~a @ ~a(~a); free ~a(~a) ~ams @ ~a"
-                                           (if minor? "min" "MAJ") gen
+                                            (if minor? "min" "MAJ") gen
-                                           (K "" pre-allocated) (K "+" (- pre-allocated+overhead pre-allocated))
+                                            (K "" pre-allocated) (K "+" (- pre-allocated+overhead pre-allocated))
-                                           (K "" delta) (K "+" (- (- pre-allocated+overhead post-allocated+overhead)
+                                            (K "" delta) (K "+" (- (- pre-allocated+overhead post-allocated+overhead)
-                                                                  delta))
+                                                                   delta))
-                                           (- post-cpu-time pre-cpu-time) pre-cpu-time)
+                                            (- post-cpu-time pre-cpu-time) pre-cpu-time)
-                              (make-gc-info (if minor? 'minor 'major) pre-allocated pre-allocated+overhead 0
+                               (make-gc-info (if minor? 'minor 'major) pre-allocated pre-allocated+overhead 0
-                                            post-allocated post-allocated+overhead
+                                             post-allocated post-allocated+overhead
-                                            pre-cpu-time post-cpu-time
+                                             pre-cpu-time post-cpu-time
-                                            pre-time post-time)
+                                             pre-time post-time)
-                              #f)))))))))
+                               #f
+                               ;; in interrupt:
+                               #t)))))))))
    (seq
     (|#%app| exit-handler
      (let ([orig (|#%app| exit-handler)]

racket/src/cs/rumble.sls

@@ -599,7 +599,7 @@
           set-ffi-get-lib-and-obj!        ; not exported to Racket
           poll-async-callbacks            ; not exported to Racket
           set-async-callback-poll-wakeup! ; not exported to Racket
-          set-foreign-eval!               ; not exported to racket
+          set-foreign-eval!               ; not exported to Racket
 
           unsafe-unbox
           unsafe-unbox*

racket/src/cs/rumble/memory.ss

@@ -307,28 +307,32 @@
 
 ;; ----------------------------------------
 
-;; List of (cons <pre> <post>)
+;; List of (cons <pre> <post>), currently suported
+;; only in the original host thread of the original place
 (define collect-callbacks '())
 
 (define (unsafe-add-collect-callbacks pre post)
-  (let ([p (cons pre post)])
+  (when (in-original-host-thread?)
-    (with-interrupts-disabled
+    (let ([p (cons pre post)])
-     (set! collect-callbacks (cons p collect-callbacks)))
+      (with-interrupts-disabled
-    p))
+       (set! collect-callbacks (cons p collect-callbacks)))
+      p)))
 
 (define (unsafe-remove-collect-callbacks p)
-  (with-interrupts-disabled
+  (when (in-original-host-thread?)
-   (set! collect-callbacks (#%remq p collect-callbacks))))
+    (with-interrupts-disabled
+     (set! collect-callbacks (#%remq p collect-callbacks)))))
 
 (define (run-collect-callbacks sel)
-  (let loop ([l collect-callbacks])
+  (when (in-original-host-thread?)
-    (unless (null? l)
+    (let loop ([l collect-callbacks])
-      (let ([v (sel (car l))])
+      (unless (null? l)
-        (let loop ([i 0] [save #f])
+        (let ([v (sel (car l))])
-          (unless (fx= i (#%vector-length v))
+          (let loop ([i 0] [save #f])
-            (loop (fx+ i 1)
+            (unless (fx= i (#%vector-length v))
-                  (run-one-collect-callback (#%vector-ref v i) save sel))))
+              (loop (fx+ i 1)
-        (loop (cdr l))))))
+                    (run-one-collect-callback (#%vector-ref v i) save sel))))
+          (loop (cdr l)))))))
 
 (define-syntax (osapi-foreign-procedure stx)
   (syntax-case stx ()

racket/src/cs/rumble/pthread.ss

@@ -8,6 +8,10 @@
                      (set-place-registers! place-registers)
                      (thunk)))))
   (define pthread? thread?)
+  (define in-original-host-thread?
+    (let ([initial-thread-id (get-thread-id)])
+      (lambda ()
+        (eqv? (get-thread-id) initial-thread-id))))
   ;; make-condition
   ;; condition-wait
   ;; condition-signal
@@ -20,6 +24,7 @@
   (define make-pthread-parameter #%make-parameter)
   (define (fork-pthread) (void))
   (define (pthread?) #f)
+  (define (in-original-host-thread?) #t)
   (define (make-condition) (void))
   (define (condition-wait c m) (void))
   (define (condition-signal c) (void))

racket/src/io/host/bootstrap.rkt

@@ -132,5 +132,6 @@
                          'unsafe-custodian-unregister unsafe-custodian-unregister
                          'thread-push-kill-callback! thread-push-kill-callback!
                          'thread-pop-kill-callback! thread-pop-kill-callback!
+                         'unsafe-add-pre-poll-callback! (lambda (proc) (void))
                          'set-get-subprocesses-time! void
                          'prop:place-message prop:place-message))

racket/src/io/host/thread.rkt

@@ -78,6 +78,7 @@
          unsafe-custodian-unregister
          thread-push-kill-callback!
          thread-pop-kill-callback!
+         unsafe-add-pre-poll-callback!
          set-get-subprocesses-time!)
 
 (define start-atomic unsafe-start-atomic)

racket/src/io/logger/main.rkt

@@ -15,7 +15,8 @@
          log-max-level
          log-all-levels
          log-level-evt
-         log-message  ; ok to call in host-Scheme interrupt handler
+         log-message
+         log-message* ; ok to call in host-Scheme interrupt handler
          log-receiver?
          make-log-receiver
          add-stderr-log-receiver!
@@ -80,8 +81,6 @@
         s])))
   (semaphore-peek-evt s))
 
-;; Can be called in any host Scheme thread and in interrupt handler,
-;; like `log-level?`:
 (define/who log-message
   ;; Complex dispatch based on number and whether third is a string:
   (case-lambda
@@ -102,13 +101,16 @@
     [(logger level topic message data prefix?)
      (do-log-message who logger level topic message data prefix?)]))
 
-;; Can be called in any host Scheme thread and in interrupt handler,
-;; like `log-level?`:
 (define (do-log-message who logger level topic message data prefix?)
   (check who logger? logger)
   (check-level who level)
   (check who #:or-false symbol? topic)
   (check who string? message)
+  (log-message* logger level topic message data prefix? #f))
+
+;; Can be called in any host Scheme thread and in interrupt handler,
+;; like `log-level?`:
+(define (log-message* logger level topic message data prefix? in-interrupt?)
   (define msg #f)
   (atomically/no-interrupts/no-wind
    (when ((logger-max-wanted-level logger) . level>=? . level)
@@ -126,7 +128,7 @@
                              message))
                         data
                         topic)))
-           (log-receiver-send! r msg)))
+           (log-receiver-send! r msg in-interrupt?)))
        (let ([parent (logger-parent logger)])
          (when (and parent
                     ((filters-level-for-topic (logger-propagate-filters logger) topic) . level>=? . level))

racket/src/io/logger/receiver.rkt

@@ -2,6 +2,7 @@
 (require "../common/check.rkt"
          "../../common/queue.rkt"
          "../host/thread.rkt"
+         "../host/pthread.rkt"
          "../host/rktio.rkt"
          "../string/convert.rkt"
          "level.rkt"
@@ -27,48 +28,44 @@
   #:property
   prop:receiver-send
   (lambda (lr msg)
-    ;; called in atomic mode and possibly in host interrupt handler,
+    ;; called in atomic mode
-    ;; so anything we touch here should only be modified with
+    (define b (queue-remove! (queue-log-receiver-waiters lr)))
-    ;; interrupts disabled
+    (cond
-    (atomically/no-interrupts/no-wind
+      [b
-     (define b (queue-remove! (queue-log-receiver-waiters lr)))
+       (decrement-receiever-waiters! lr)
-     (cond
+       (define select! (unbox b))
-       [b
+       (set-box! b msg)
-        (decrement-receiever-waiters! lr)
+       (select!)]
-        (define select! (unbox b))
+      [else
-        (set-box! b msg)
+       (queue-add! (queue-log-receiver-msgs lr) msg)]))
-        (select!)]
-       [else
-        (queue-add! (queue-log-receiver-msgs lr) msg)])))
   #:property
   prop:evt
   (poller (lambda (lr ctx)
-            (define msg (atomically/no-interrupts/no-wind (queue-remove! (queue-log-receiver-msgs lr))))
+            (define msg (queue-remove! (queue-log-receiver-msgs lr)))
             (cond
               [msg
                (values (list msg) #f)]
               [else
                (define b (box (poll-ctx-select-proc ctx)))
-               (define n (atomically/no-interrupts/no-wind
+               (define n (begin
-                          (increment-receiever-waiters! lr)
+                           (increment-receiever-waiters! lr)
-                          (queue-add! (queue-log-receiver-waiters lr) b)))
+                           (queue-add! (queue-log-receiver-waiters lr) b)))
                (values #f (control-state-evt
                            (wrap-evt async-evt (lambda (e) (unbox b)))
-                           (lambda () (atomically/no-interrupts/no-wind
+                           (lambda ()
-                                       (queue-remove-node! (queue-log-receiver-waiters lr) n)
+                             (queue-remove-node! (queue-log-receiver-waiters lr) n)
-                                       (decrement-receiever-waiters! lr)))
+                             (decrement-receiever-waiters! lr))
                            void
                            (lambda ()
-                             (atomically/no-interrupts/no-wind
+                             (define msg (queue-remove! (queue-log-receiver-msgs lr)))
-                              (define msg (queue-remove! (queue-log-receiver-msgs lr)))
+                             (cond
-                              (cond
+                               [msg
-                                [msg
+                                (set-box! b msg)
-                                 (set-box! b msg)
+                                (values msg #t)]
-                                 (values msg #t)]
+                               [else
-                                [else
+                                (increment-receiever-waiters! lr)
-                                 (increment-receiever-waiters! lr)
+                                (set! n (queue-add! (queue-log-receiver-waiters lr) b))
-                                 (set! n (queue-add! (queue-log-receiver-waiters lr) b))
+                                (values #f #f)]))))]))))
-                                 (values #f #f)])))))]))))
 
 (define/who (make-log-receiver logger level . args)
   (check who logger? logger)
@@ -152,5 +149,11 @@
      (set-logger-level-sema! logger #f))))
 
 ;; Called in atomic mode and with interrupts disabled
-(define (log-receiver-send! r msg)
+(define (log-receiver-send! r msg in-interrupt?)
-  ((receiver-send-ref r) r msg))
+  (if (or (not in-interrupt?)
+          ;; We can run stdio loggers in atomic/interrupt mode:
+          (stdio-log-receiver? r))
+      ((receiver-send-ref r) r msg)
+      ;; Record any any other message for posting later:
+      (unsafe-add-pre-poll-callback! (lambda ()
+                                       ((receiver-send-ref r) r msg)))))

racket/src/thread/instance.rkt

@@ -11,7 +11,8 @@
          "thread.rkt"
          "unsafe.rkt"
          "time.rkt"
-         "place-message.rkt")
+         "place-message.rkt"
+         "pre-poll.rkt")
 
 ;; Unsafe scheduler-cooperation functions are made available to
 ;; clients through a `#%thread` primitive linklet instance:
@@ -65,5 +66,6 @@
           'unsafe-custodian-unregister unsafe-custodian-unregister
           'thread-push-kill-callback! thread-push-kill-callback!
           'thread-pop-kill-callback! thread-pop-kill-callback!
+          'unsafe-add-pre-poll-callback! unsafe-add-pre-poll-callback!
           'set-get-subprocesses-time! set-get-subprocesses-time!
           'prop:place-message prop:place-message))

racket/src/thread/place.rkt

@@ -95,6 +95,7 @@
   (start-atomic)
   (define-values (parent-in parent-out parent-err child-in-fd child-out-fd child-err-fd)
     (make-place-ports+fds in out err))
+  (host:mutex-acquire lock)
   ;; Start the new place
   (host:fork-place
    (lambda ()
@@ -136,7 +137,6 @@
        (wakeup-waiting pl))
      (hash-clear! done-waiting)))
   ;; Wait for the place to start, then return the place object
-  (host:mutex-acquire lock)
   (host:condition-wait started lock)
   (host:mutex-release lock)
   (end-atomic)

racket/src/thread/pre-poll.rkt

@@ -0,0 +1,26 @@
+#lang racket/base
+(require "atomic.rkt"
+         "host.rkt")
+
+(provide unsafe-add-pre-poll-callback!
+         call-pre-poll-external-callbacks)
+
+(define pre-poll-callbacks null)
+
+;; called in atomic mode in an arbitrary host thread, but
+;; with all other host threads paused; the given procedure
+;; will be called in atomic mode, possibly in the schduler
+(define (unsafe-add-pre-poll-callback! proc)
+  (set! pre-poll-callbacks (cons proc pre-poll-callbacks)))
+
+;; in atomic mode
+(define (call-pre-poll-external-callbacks)
+  (unless (null? pre-poll-callbacks)
+    ;; disable interrupts to avoid a case with `unsafe-add-pre-poll-callback!`
+    (host:disable-interrupts)
+    (define l pre-poll-callbacks)
+    (set! pre-poll-callbacks null)
+    (host:enable-interrupts)
+    ;; Call the callbacks
+    (for ([cb (in-list (reverse l))])
+      (cb))))

racket/src/thread/schedule.rkt

@@ -12,7 +12,8 @@
          "exit.rkt"
          "future.rkt"
          "custodian.rkt"
-         (submod "custodian.rkt" scheduling))
+         (submod "custodian.rkt" scheduling)
+         "pre-poll.rkt")
 
 ;; Many scheduler details are implemented in "thread.rkt", but this
 ;; module handles the thread selection, thread swapping, and
@@ -48,6 +49,7 @@
                           pending-callbacks))
     (host:poll-will-executors)
     (check-external-events 'fast)
+    (call-pre-poll-external-callbacks)
     (check-place-activity)
     (when (and (null? callbacks)
                (all-threads-poll-done?)

racket/src/thread/semaphore.rkt

@@ -5,7 +5,8 @@
          "atomic.rkt"
          "parameter.rkt"
          "waiter.rkt"
-         "evt.rkt")
+         "evt.rkt"
+         "pre-poll.rkt")
 
 (provide make-semaphore
          semaphore?
@@ -93,6 +94,7 @@
 (define/who (semaphore-try-wait? s)
   (check who semaphore? s)
   (atomically
+   (call-pre-poll-external-callbacks)
    (define c (semaphore-count s))
    (cond
      [(positive? c)

racket/src/thread/sync.rkt

@@ -9,7 +9,8 @@
          "thread.rkt"
          (only-in (submod "thread.rkt" scheduling)
                   thread-descheduled?)
-         "schedule-info.rkt")
+         "schedule-info.rkt"
+         "pre-poll.rkt")
 
 (provide sync
          sync/timeout
@@ -96,6 +97,7 @@
        (cond
          [(or (and (real? timeout) (zero? timeout))
               (procedure? timeout))
+          (atomically (call-pre-poll-external-callbacks))
           (let poll-loop ()
             (sync-poll s #:fail-k (lambda (sched-info polled-all?)
                                     (cond