fix (#220) ?

If an actor ends right after a dsend, the Comm should not be canceled
to let the receiver a chance to catch it.

It was removed in Comm::cancel(), now it's not, and the destructor has
to be a bit more careful.

As the comm was canceled, if the receive is posted later, it nevers
find its matching send and may stall forever or timeout.

This changed the output of the chord example (using dsend), but I
suspect it was not so correct before with some dsend being canceled
and the corresponding receive ending on timeout.

This also highlighted an issue in Java. The cleanup function for dsend
is now called at the end of the simulation and get_current_thread_env
crashed (because the current thread is maestro).

Hopefully, this commit does not cause new leaks.

diff --git a/examples/s4u/dht-chord/s4u-dht-chord.tesh b/examples/s4u/dht-chord/s4u-dht-chord.tesh
index 5f7aaa8..dab06c1 100644 (file)
--- a/examples/s4u/dht-chord/s4u-dht-chord.tesh
+++ b/examples/s4u/dht-chord/s4u-dht-chord.tesh
@@ -96,7 +96,6 @@ $ $SG_TEST_EXENV ${bindir:=.}/s4u-dht-chord$EXEEXT -nb_bits=3 ${platfdir}/cluste
 > [ 230.07446] (node@node-0.simgrid.org)    4  |  42
 > [ 230.07446] (node@node-0.simgrid.org)    6  |  42
 > [ 230.07446] (node@node-0.simgrid.org) Predecessor: 533744
-> [ 235.08217] (node@node-4.simgrid.org) My new finger #0 is 533744
 > [ 240.08987] (node@node-0.simgrid.org) My new finger #1 is 16509405
 > [ 240.08987] (node@node-0.simgrid.org) My finger table:
 > [ 240.08987] (node@node-0.simgrid.org) Start | Succ
@@ -112,126 +111,120 @@ $ $SG_TEST_EXENV ${bindir:=.}/s4u-dht-chord$EXEEXT -nb_bits=3 ${platfdir}/cluste
 > [ 255.11299] (node@node-5.simgrid.org)    6  | 10874876
 > [ 255.11299] (node@node-5.simgrid.org)    0  | 10874876
 > [ 255.11299] (node@node-5.simgrid.org) Predecessor: -1
-> [ 265.09718] (node@node-2.simgrid.org) My new predecessor is 16509405
-> [ 265.09718] (node@node-2.simgrid.org) My finger table:
-> [ 265.09718] (node@node-2.simgrid.org) Start | Succ
-> [ 265.09718] (node@node-2.simgrid.org)    1  |  42
-> [ 265.09718] (node@node-2.simgrid.org)    2  | 533744
-> [ 265.09718] (node@node-2.simgrid.org)    4  | 533744
-> [ 265.09718] (node@node-2.simgrid.org) Predecessor: 16509405
-> [ 275.11259] (node@node-5.simgrid.org) My new finger #0 is 42
-> [ 280.10468] (node@node-4.simgrid.org) My new predecessor is 10874876
-> [ 280.10468] (node@node-4.simgrid.org) My finger table:
-> [ 280.10468] (node@node-4.simgrid.org) Start | Succ
-> [ 280.10468] (node@node-4.simgrid.org)    6  | 533744
-> [ 280.10468] (node@node-4.simgrid.org)    7  | 16509405
-> [ 280.10468] (node@node-4.simgrid.org)    1  | 16509405
-> [ 280.10468] (node@node-4.simgrid.org) Predecessor: 10874876
-> [ 285.13581] (node@node-4.simgrid.org) My new predecessor is 42
-> [ 285.13581] (node@node-4.simgrid.org) My finger table:
-> [ 285.13581] (node@node-4.simgrid.org) Start | Succ
-> [ 285.13581] (node@node-4.simgrid.org)    6  | 533744
-> [ 285.13581] (node@node-4.simgrid.org)    7  | 16509405
-> [ 285.13581] (node@node-4.simgrid.org)    1  | 16509405
-> [ 285.13581] (node@node-4.simgrid.org) Predecessor: 42
-> [ 300.13551] (node@node-4.simgrid.org) My new finger #1 is 533744
-> [ 300.13551] (node@node-4.simgrid.org) My finger table:
-> [ 300.13551] (node@node-4.simgrid.org) Start | Succ
-> [ 300.13551] (node@node-4.simgrid.org)    6  | 533744
-> [ 300.13551] (node@node-4.simgrid.org)    7  | 533744
-> [ 300.13551] (node@node-4.simgrid.org)    1  | 16509405
-> [ 300.13551] (node@node-4.simgrid.org) Predecessor: 42
-> [ 300.14332] (node@node-2.simgrid.org) My new finger #1 is 42
-> [ 300.14332] (node@node-2.simgrid.org) My finger table:
-> [ 300.14332] (node@node-2.simgrid.org) Start | Succ
-> [ 300.14332] (node@node-2.simgrid.org)    1  |  42
-> [ 300.14332] (node@node-2.simgrid.org)    2  |  42
-> [ 300.14332] (node@node-2.simgrid.org)    4  | 533744
-> [ 300.14332] (node@node-2.simgrid.org) Predecessor: 16509405
-> [ 305.14322] (node@node-5.simgrid.org) My new finger #0 is 533744
-> [ 305.15102] (node@node-0.simgrid.org) My new finger #0 is 10874876
-> [ 310.15873] (node@node-6.simgrid.org) My new finger #1 is 42
-> [ 310.15873] (node@node-6.simgrid.org) My finger table:
-> [ 310.15873] (node@node-6.simgrid.org) Start | Succ
-> [ 310.15873] (node@node-6.simgrid.org)    1  |  42
-> [ 310.15873] (node@node-6.simgrid.org)    2  |  42
-> [ 310.15873] (node@node-6.simgrid.org)    4  | 16728096
-> [ 310.15873] (node@node-6.simgrid.org) Predecessor: -1
-> [ 330.16613] (node@node-5.simgrid.org) My new finger #0 is 16509405
-> [ 335.16603] (node@node-5.simgrid.org) My new predecessor is 42
-> [ 335.16603] (node@node-5.simgrid.org) My finger table:
-> [ 335.16603] (node@node-5.simgrid.org) Start | Succ
-> [ 335.16603] (node@node-5.simgrid.org)    5  | 16509405
-> [ 335.16603] (node@node-5.simgrid.org)    6  | 10874876
-> [ 335.16603] (node@node-5.simgrid.org)    0  | 10874876
-> [ 335.16603] (node@node-5.simgrid.org) Predecessor: 42
-> [ 340.16593] (node@node-4.simgrid.org) Well Guys! I Think it's time for me to leave ;)
-> [ 350.15793] (node@node-2.simgrid.org) My new predecessor is 42
-> [ 350.16573] (node@node-0.simgrid.org) My new finger #0 is 533744
-> [ 360.18115] (node@node-0.simgrid.org) My new finger #2 is 533744
-> [ 360.18115] (node@node-0.simgrid.org) My finger table:
-> [ 360.18115] (node@node-0.simgrid.org) Start | Succ
-> [ 360.18115] (node@node-0.simgrid.org)    3  | 533744
-> [ 360.18115] (node@node-0.simgrid.org)    4  | 16509405
-> [ 360.18115] (node@node-0.simgrid.org)    6  | 533744
-> [ 360.18115] (node@node-0.simgrid.org) Predecessor: 533744
-> [ 420.23459] (node@node-2.simgrid.org) Well Guys! I Think it's time for me to leave ;)
-> [ 425.22668] (node@node-0.simgrid.org) My new predecessor is 42
-> [ 475.22668] (node@node-0.simgrid.org) My new finger #0 is 42
-> [ 480.22658] (node@node-0.simgrid.org) My new predecessor is 16728096
-> [ 480.22658] (node@node-0.simgrid.org) My finger table:
-> [ 480.22658] (node@node-0.simgrid.org) Start | Succ
-> [ 480.22658] (node@node-0.simgrid.org)    3  |  42
-> [ 480.22658] (node@node-0.simgrid.org)    4  | 16509405
-> [ 480.22658] (node@node-0.simgrid.org)    6  | 533744
-> [ 480.22658] (node@node-0.simgrid.org) Predecessor: 16728096
-> [ 485.23429] (node@node-6.simgrid.org) My new finger #2 is 42
-> [ 485.23429] (node@node-6.simgrid.org) My finger table:
-> [ 485.23429] (node@node-6.simgrid.org) Start | Succ
-> [ 485.23429] (node@node-6.simgrid.org)    1  |  42
-> [ 485.23429] (node@node-6.simgrid.org)    2  |  42
-> [ 485.23429] (node@node-6.simgrid.org)    4  |  42
-> [ 485.23429] (node@node-6.simgrid.org) Predecessor: -1
-> [ 495.24189] (node@node-0.simgrid.org) My new finger #0 is 16728096
-> [ 575.25691] (node@node-6.simgrid.org) My new predecessor is 42
-> [ 575.25691] (node@node-6.simgrid.org) My finger table:
-> [ 575.25691] (node@node-6.simgrid.org) Start | Succ
-> [ 575.25691] (node@node-6.simgrid.org)    1  |  42
-> [ 575.25691] (node@node-6.simgrid.org)    2  |  42
-> [ 575.25691] (node@node-6.simgrid.org)    4  |  42
-> [ 575.25691] (node@node-6.simgrid.org) Predecessor: 42
-> [ 600.26421] (node@node-0.simgrid.org) My new finger #1 is 16728096
-> [ 600.26421] (node@node-0.simgrid.org) My finger table:
-> [ 600.26421] (node@node-0.simgrid.org) Start | Succ
-> [ 600.26421] (node@node-0.simgrid.org)    3  | 16728096
-> [ 600.26421] (node@node-0.simgrid.org)    4  | 16728096
-> [ 600.26421] (node@node-0.simgrid.org)    6  | 533744
-> [ 600.26421] (node@node-0.simgrid.org) Predecessor: 16728096
-> [ 720.35548] (node@node-0.simgrid.org) My new finger #2 is 16728096
-> [ 720.35548] (node@node-0.simgrid.org) My finger table:
-> [ 720.35548] (node@node-0.simgrid.org) Start | Succ
-> [ 720.35548] (node@node-0.simgrid.org)    3  | 16728096
-> [ 720.35548] (node@node-0.simgrid.org)    4  | 16728096
-> [ 720.35548] (node@node-0.simgrid.org)    6  | 16728096
-> [ 720.35548] (node@node-0.simgrid.org) Predecessor: 16728096
-> [ 855.45426] (node@node-6.simgrid.org) My new finger #2 is 16728096
-> [ 855.45426] (node@node-6.simgrid.org) My finger table:
-> [ 855.45426] (node@node-6.simgrid.org) Start | Succ
-> [ 855.45426] (node@node-6.simgrid.org)    1  |  42
-> [ 855.45426] (node@node-6.simgrid.org)    2  |  42
-> [ 855.45426] (node@node-6.simgrid.org)    4  | 16728096
-> [ 855.45426] (node@node-6.simgrid.org) Predecessor: 42
-> [ 860.45416] (node@node-6.simgrid.org) Well Guys! I Think it's time for me to leave ;)
-> [ 865.44626] (node@node-0.simgrid.org) My new predecessor is 42
-> [ 890.42334] (node@node-5.simgrid.org) Well Guys! I Think it's time for me to leave ;)
-> [ 915.44626] (node@node-0.simgrid.org) My new finger #0 is 42
-> [ 940.44576] (node@node-0.simgrid.org) My new finger #0 is 16509405
-> [ 990.44576] (node@node-0.simgrid.org) My new finger #1 is 16509405
-> [ 990.44576] (node@node-0.simgrid.org) My finger table:
-> [ 990.44576] (node@node-0.simgrid.org) Start | Succ
-> [ 990.44576] (node@node-0.simgrid.org)    3  | 16509405
-> [ 990.44576] (node@node-0.simgrid.org)    4  | 16509405
-> [ 990.44576] (node@node-0.simgrid.org)    6  | 16728096
-> [ 990.44576] (node@node-0.simgrid.org) Predecessor: 42
-> [1040.44576] (node@node-0.simgrid.org) Well Guys! I Think it's time for me to leave ;)
-> [1090.44576] (maestro@) Simulated time: 1090.45
+> [ 255.13641] (node@node-4.simgrid.org) My new finger #0 is 533744
+> [ 270.14391] (node@node-5.simgrid.org) My new finger #0 is 42
+> [ 275.13601] (node@node-4.simgrid.org) My new predecessor is 10874876
+> [ 275.13601] (node@node-4.simgrid.org) My finger table:
+> [ 275.13601] (node@node-4.simgrid.org) Start | Succ
+> [ 275.13601] (node@node-4.simgrid.org)    6  | 533744
+> [ 275.13601] (node@node-4.simgrid.org)    7  | 16509405
+> [ 275.13601] (node@node-4.simgrid.org)    1  | 16509405
+> [ 275.13601] (node@node-4.simgrid.org) Predecessor: 10874876
+> [ 280.15152] (node@node-4.simgrid.org) My new predecessor is 42
+> [ 280.15152] (node@node-4.simgrid.org) My finger table:
+> [ 280.15152] (node@node-4.simgrid.org) Start | Succ
+> [ 280.15152] (node@node-4.simgrid.org)    6  | 533744
+> [ 280.15152] (node@node-4.simgrid.org)    7  | 16509405
+> [ 280.15152] (node@node-4.simgrid.org)    1  | 16509405
+> [ 280.15152] (node@node-4.simgrid.org) Predecessor: 42
+> [ 290.12790] (node@node-2.simgrid.org) My new predecessor is 16509405
+> [ 290.12790] (node@node-2.simgrid.org) My finger table:
+> [ 290.12790] (node@node-2.simgrid.org) Start | Succ
+> [ 290.12790] (node@node-2.simgrid.org)    1  |  42
+> [ 290.12790] (node@node-2.simgrid.org)    2  | 533744
+> [ 290.12790] (node@node-2.simgrid.org)    4  | 533744
+> [ 290.12790] (node@node-2.simgrid.org) Predecessor: 16509405
+> [ 300.14331] (node@node-2.simgrid.org) My new finger #1 is 42
+> [ 300.14331] (node@node-2.simgrid.org) My finger table:
+> [ 300.14331] (node@node-2.simgrid.org) Start | Succ
+> [ 300.14331] (node@node-2.simgrid.org)    1  |  42
+> [ 300.14331] (node@node-2.simgrid.org)    2  |  42
+> [ 300.14331] (node@node-2.simgrid.org)    4  | 533744
+> [ 300.14331] (node@node-2.simgrid.org) Predecessor: 16509405
+> [ 300.15112] (node@node-4.simgrid.org) My new finger #1 is 533744
+> [ 300.15112] (node@node-4.simgrid.org) My finger table:
+> [ 300.15112] (node@node-4.simgrid.org) Start | Succ
+> [ 300.15112] (node@node-4.simgrid.org)    6  | 533744
+> [ 300.15112] (node@node-4.simgrid.org)    7  | 533744
+> [ 300.15112] (node@node-4.simgrid.org)    1  | 16509405
+> [ 300.15112] (node@node-4.simgrid.org) Predecessor: 42
+> [ 305.14321] (node@node-5.simgrid.org) My new finger #0 is 533744
+> [ 305.16663] (node@node-0.simgrid.org) My new finger #0 is 10874876
+> [ 310.17434] (node@node-6.simgrid.org) My new finger #1 is 42
+> [ 310.17434] (node@node-6.simgrid.org) My finger table:
+> [ 310.17434] (node@node-6.simgrid.org) Start | Succ
+> [ 310.17434] (node@node-6.simgrid.org)    1  |  42
+> [ 310.17434] (node@node-6.simgrid.org)    2  |  42
+> [ 310.17434] (node@node-6.simgrid.org)    4  | 16728096
+> [ 310.17434] (node@node-6.simgrid.org) Predecessor: -1
+> [ 340.18155] (node@node-5.simgrid.org) My new finger #0 is 16509405
+> [ 340.18935] (node@node-4.simgrid.org) Well Guys! I Think it's time for me to leave ;)
+> [ 345.18145] (node@node-5.simgrid.org) My new predecessor is 42
+> [ 345.18145] (node@node-5.simgrid.org) My finger table:
+> [ 345.18145] (node@node-5.simgrid.org) Start | Succ
+> [ 345.18145] (node@node-5.simgrid.org)    5  | 16509405
+> [ 345.18145] (node@node-5.simgrid.org)    6  | 10874876
+> [ 345.18145] (node@node-5.simgrid.org)    0  | 10874876
+> [ 345.18145] (node@node-5.simgrid.org) Predecessor: 42
+> [ 350.17354] (node@node-2.simgrid.org) My new predecessor is 42
+> [ 350.18135] (node@node-0.simgrid.org) My new finger #0 is 533744
+> [ 360.19676] (node@node-0.simgrid.org) My new finger #2 is 533744
+> [ 360.19676] (node@node-0.simgrid.org) My finger table:
+> [ 360.19676] (node@node-0.simgrid.org) Start | Succ
+> [ 360.19676] (node@node-0.simgrid.org)    3  | 533744
+> [ 360.19676] (node@node-0.simgrid.org)    4  | 16509405
+> [ 360.19676] (node@node-0.simgrid.org)    6  | 533744
+> [ 360.19676] (node@node-0.simgrid.org) Predecessor: 533744
+> [ 420.25020] (node@node-2.simgrid.org) Well Guys! I Think it's time for me to leave ;)
+> [ 425.24229] (node@node-0.simgrid.org) My new predecessor is 42
+> [ 475.24229] (node@node-0.simgrid.org) My new finger #0 is 42
+> [ 480.24219] (node@node-0.simgrid.org) My new predecessor is 16728096
+> [ 480.24219] (node@node-0.simgrid.org) My finger table:
+> [ 480.24219] (node@node-0.simgrid.org) Start | Succ
+> [ 480.24219] (node@node-0.simgrid.org)    3  |  42
+> [ 480.24219] (node@node-0.simgrid.org)    4  | 16509405
+> [ 480.24219] (node@node-0.simgrid.org)    6  | 533744
+> [ 480.24219] (node@node-0.simgrid.org) Predecessor: 16728096
+> [ 485.24990] (node@node-6.simgrid.org) My new finger #2 is 42
+> [ 485.24990] (node@node-6.simgrid.org) My finger table:
+> [ 485.24990] (node@node-6.simgrid.org) Start | Succ
+> [ 485.24990] (node@node-6.simgrid.org)    1  |  42
+> [ 485.24990] (node@node-6.simgrid.org)    2  |  42
+> [ 485.24990] (node@node-6.simgrid.org)    4  |  42
+> [ 485.24990] (node@node-6.simgrid.org) Predecessor: -1
+> [ 495.25751] (node@node-0.simgrid.org) My new finger #0 is 16728096
+> [ 525.28032] (node@node-6.simgrid.org) My new predecessor is 42
+> [ 525.28032] (node@node-6.simgrid.org) My finger table:
+> [ 525.28032] (node@node-6.simgrid.org) Start | Succ
+> [ 525.28032] (node@node-6.simgrid.org)    1  |  42
+> [ 525.28032] (node@node-6.simgrid.org)    2  |  42
+> [ 525.28032] (node@node-6.simgrid.org)    4  |  42
+> [ 525.28032] (node@node-6.simgrid.org) Predecessor: 42
+> [ 600.31785] (node@node-0.simgrid.org) My new finger #1 is 16728096
+> [ 600.31785] (node@node-0.simgrid.org) My finger table:
+> [ 600.31785] (node@node-0.simgrid.org) Start | Succ
+> [ 600.31785] (node@node-0.simgrid.org)    3  | 16728096
+> [ 600.31785] (node@node-0.simgrid.org)    4  | 16728096
+> [ 600.31785] (node@node-0.simgrid.org)    6  | 533744
+> [ 600.31785] (node@node-0.simgrid.org) Predecessor: 16728096
+> [ 720.40913] (node@node-0.simgrid.org) My new finger #2 is 16728096
+> [ 720.40913] (node@node-0.simgrid.org) My finger table:
+> [ 720.40913] (node@node-0.simgrid.org) Start | Succ
+> [ 720.40913] (node@node-0.simgrid.org)    3  | 16728096
+> [ 720.40913] (node@node-0.simgrid.org)    4  | 16728096
+> [ 720.40913] (node@node-0.simgrid.org)    6  | 16728096
+> [ 720.40913] (node@node-0.simgrid.org) Predecessor: 16728096
+> [ 850.49239] (node@node-5.simgrid.org) Well Guys! I Think it's time for me to leave ;)
+> [ 855.50791] (node@node-6.simgrid.org) My new finger #2 is 16728096
+> [ 855.50791] (node@node-6.simgrid.org) My finger table:
+> [ 855.50791] (node@node-6.simgrid.org) Start | Succ
+> [ 855.50791] (node@node-6.simgrid.org)    1  |  42
+> [ 855.50791] (node@node-6.simgrid.org)    2  |  42
+> [ 855.50791] (node@node-6.simgrid.org)    4  | 16728096
+> [ 855.50791] (node@node-6.simgrid.org) Predecessor: 42
+> [ 860.50781] (node@node-6.simgrid.org) Well Guys! I Think it's time for me to leave ;)
+> [ 865.49990] (node@node-0.simgrid.org) My new predecessor is 42
+> [ 915.49990] (node@node-0.simgrid.org) My new finger #0 is 42
+> [ 920.49980] (node@node-0.simgrid.org) My new finger #0 is 16509405
+> [1030.49960] (node@node-0.simgrid.org) Well Guys! I Think it's time for me to leave ;)
+> [1080.49960] (maestro@) Simulated time: 1080.5

diff --git a/src/bindings/java/jmsg.cpp b/src/bindings/java/jmsg.cpp
index 4b81f4e..31d5ba8 100644 (file)
--- a/src/bindings/java/jmsg.cpp
+++ b/src/bindings/java/jmsg.cpp
@@ -51,7 +51,10 @@ JNIEnv *get_current_thread_env()
 {
   using simgrid::kernel::context::JavaContext;
   JavaContext* ctx = static_cast<JavaContext*>(simgrid::kernel::context::Context::self());
-  return ctx->jenv_;
+  if (ctx)
+    return ctx->jenv_;
+  else
+    return nullptr;
 }
 
 void jmsg_throw_status(JNIEnv *env, msg_error_t status) {

diff --git a/src/bindings/java/jmsg_task.cpp b/src/bindings/java/jmsg_task.cpp
index b017a48..77edf00 100644 (file)
--- a/src/bindings/java/jmsg_task.cpp
+++ b/src/bindings/java/jmsg_task.cpp
@@ -470,16 +470,17 @@ JNIEXPORT void JNICALL Java_org_simgrid_msg_Task_nativeFinalize(JNIEnv * env, jo
 
 static void msg_task_cancel_on_failed_dsend(void*t) {
   msg_task_t task = (msg_task_t) t;
-  JNIEnv *env =get_current_thread_env();
-  jobject jtask_global = (jobject) MSG_task_get_data(task);
-
-  /* Destroy the global ref so that the JVM can free the stuff */
-  env->DeleteGlobalRef(jtask_global);
+  JNIEnv* env     = get_current_thread_env();
+  if (env) {
+    jobject jtask_global = (jobject)MSG_task_get_data(task);
+    /* Destroy the global ref so that the JVM can free the stuff */
+    env->DeleteGlobalRef(jtask_global);
+    /* Don't free the C data here, to avoid a race condition with the GC also sometimes doing so.
+     * A rare memleak is seen as preferable to a rare "free(): invalid pointer" failure that
+     * proves really hard to debug.
+     */
+  }
   MSG_task_set_data(task, nullptr);
-  /* Don't free the C data here, to avoid a race condition with the GC also sometimes doing so.
-   * A rare memleak is seen as preferable to a rare "free(): invalid pointer" failure that
-   * proves really hard to debug.
-   */
 }
 
 JNIEXPORT void JNICALL Java_org_simgrid_msg_Task_dsend(JNIEnv * env, jobject jtask, jstring jalias)

diff --git a/src/kernel/activity/CommImpl.cpp b/src/kernel/activity/CommImpl.cpp
index 069fa21..5fbd6b3 100644 (file)
--- a/src/kernel/activity/CommImpl.cpp
+++ b/src/kernel/activity/CommImpl.cpp
@@ -377,7 +377,8 @@ CommImpl::CommImpl(CommImpl::Type type) : type(type)
 
 CommImpl::~CommImpl()
 {
-  XBT_DEBUG("Really free communication %p", this);
+  XBT_DEBUG("Really free communication %p in state %d (detached = %d)", this, static_cast<int>(state_),
+            static_cast<int>(detached));
 
   cleanupSurf();
 
@@ -387,10 +388,9 @@ CommImpl::~CommImpl()
     if (clean_fun)
       clean_fun(src_buff_);
     src_buff_ = nullptr;
-  }
-
-  if (mbox)
+  } else if (mbox) {
     mbox->remove(this);
+  }
 }
 
 /**  @brief Starts the simulation of a communication synchro. */
@@ -485,8 +485,10 @@ void CommImpl::cancel()
 {
   /* if the synchro is a waiting state means that it is still in a mbox so remove from it and delete it */
   if (state_ == SIMIX_WAITING) {
-    mbox->remove(this);
-    state_ = SIMIX_CANCELED;
+    if (not detached) {
+      mbox->remove(this);
+      state_ = SIMIX_CANCELED;
+    }
   } else if (not MC_is_active() /* when running the MC there are no surf actions */
              && not MC_record_replay_is_active() && (state_ == SIMIX_READY || state_ == SIMIX_RUNNING)) {
     surf_action_->cancel();