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authorRickard Green <[email protected]>2018-03-07 01:17:21 +0100
committerRickard Green <[email protected]>2018-03-21 10:27:03 +0100
commit4bc282d812cc2c49aa3e2d073e96c720f16aa270 (patch)
treea7b00cd079368590dc09f62a4d5402be157462ca /erts/emulator/hipe
parent348a4e057db36fac13f1551c0a1c17f0d376da48 (diff)
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Implementation of true asynchronous signaling between processes
Communication between Erlang processes has conceptually always been performed through asynchronous signaling. The runtime system implementation has however previously preformed most operation synchronously. In a system with only one true thread of execution, this is not problematic (often the opposite). In a system with multiple threads of execution (as current runtime system implementation with SMP support) it becomes problematic. This since it often involves locking of structures when updating them which in turn cause resource contention. Utilizing true asynchronous communication often avoids these resource contention issues. The case that triggered this change was contention on the link lock due to frequent updates of the monitor trees during communication with a frequently used server. The signal order delivery guarantees of the language makes it hard to change the implementation of only some signals to use true asynchronous signaling. Therefore the implementations of (almost) all signals have been changed. Currently the following signals have been implemented as true asynchronous signals: - Message signals - Exit signals - Monitor signals - Demonitor signals - Monitor triggered signals (DOWN, CHANGE, etc) - Link signals - Unlink signals - Group leader signals All of the above already defined as asynchronous signals in the language. The implementation of messages signals was quite asynchronous to begin with, but had quite strict delivery constraints due to the ordering guarantees of signals between a pair of processes. The previously used message queue partitioned into two halves has been replaced by a more general signal queue partitioned into three parts that service all kinds of signals. More details regarding the signal queue can be found in comments in the erl_proc_sig_queue.h file. The monitor and link implementations have also been completely replaced in order to fit the new asynchronous signaling implementation as good as possible. More details regarding the new monitor and link implementations can be found in the erl_monitor_link.h file.
Diffstat (limited to 'erts/emulator/hipe')
-rw-r--r--erts/emulator/hipe/hipe_mkliterals.c10
-rw-r--r--erts/emulator/hipe/hipe_mode_switch.c6
-rw-r--r--erts/emulator/hipe/hipe_native_bif.c80
3 files changed, 59 insertions, 37 deletions
diff --git a/erts/emulator/hipe/hipe_mkliterals.c b/erts/emulator/hipe/hipe_mkliterals.c
index 3323e8640b..74e793577c 100644
--- a/erts/emulator/hipe/hipe_mkliterals.c
+++ b/erts/emulator/hipe/hipe_mkliterals.c
@@ -1,7 +1,7 @@
/*
* %CopyrightBegin%
*
- * Copyright Ericsson AB 2001-2016. All Rights Reserved.
+ * Copyright Ericsson AB 2001-2018. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -519,8 +519,8 @@ static const struct rts_param rts_params[] = {
1, offsetof(struct process, hipe.bif_callee)
#endif
},
- { 49, "P_MSG_FIRST", 1, offsetof(struct process, msg.first) },
- { 50, "P_MSG_SAVE", 1, offsetof(struct process, msg.save) },
+ { 49, "P_MSG_FIRST", 1, offsetof(struct process, sig_qs.first) },
+ { 50, "P_MSG_SAVE", 1, offsetof(struct process, sig_qs.save) },
{ 51, "P_CALLEE_EXP", 1, offsetof(struct process, hipe.u.callee_exp) },
{ 52, "THE_NON_VALUE", 1, (int)THE_NON_VALUE },
@@ -531,8 +531,8 @@ static const struct rts_param rts_params[] = {
#endif
},
- { 54, "P_MSG_LAST", 1, offsetof(struct process, msg.last) },
- { 55, "P_MSG_SAVED_LAST", 1, offsetof(struct process, msg.saved_last) },
+ { 54, "P_MSG_LAST", 1, offsetof(struct process, sig_qs.last) },
+ { 55, "P_MSG_SAVED_LAST", 1, offsetof(struct process, sig_qs.saved_last) },
};
#define NR_PARAMS ARRAY_SIZE(rts_params)
diff --git a/erts/emulator/hipe/hipe_mode_switch.c b/erts/emulator/hipe/hipe_mode_switch.c
index 8b497c9970..6af514d4ba 100644
--- a/erts/emulator/hipe/hipe_mode_switch.c
+++ b/erts/emulator/hipe/hipe_mode_switch.c
@@ -496,8 +496,10 @@ Process *hipe_mode_switch(Process *p, unsigned cmd, Eterm reg[])
erts_proc_lock(p, ERTS_PROC_LOCKS_MSG_RECEIVE);
p->i = hipe_beam_pc_resume;
p->arity = 0;
- erts_atomic32_read_band_relb(&p->state,
- ~ERTS_PSFLG_ACTIVE);
+ if (erts_atomic32_read_nob(&p->state) & ERTS_PSFLG_EXITING)
+ ASSERT(erts_atomic32_read_nob(&p->state) & ERTS_PSFLG_ACTIVE);
+ else
+ erts_atomic32_read_band_relb(&p->state, ~ERTS_PSFLG_ACTIVE);
erts_proc_unlock(p, ERTS_PROC_LOCKS_MSG_RECEIVE);
do_schedule:
{
diff --git a/erts/emulator/hipe/hipe_native_bif.c b/erts/emulator/hipe/hipe_native_bif.c
index 498b43ac6b..cf8c4139be 100644
--- a/erts/emulator/hipe/hipe_native_bif.c
+++ b/erts/emulator/hipe/hipe_native_bif.c
@@ -1,7 +1,7 @@
/*
* %CopyrightBegin%
*
- * Copyright Ericsson AB 2001-2017. All Rights Reserved.
+ * Copyright Ericsson AB 2001-2018. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -35,6 +35,7 @@
#include "hipe_native_bif.h"
#include "hipe_arch.h"
#include "hipe_stack.h"
+#include "erl_proc_sig_queue.h"
/*
* These are wrappers for BIFs that may trigger a native
@@ -254,7 +255,7 @@ void hipe_handle_exception(Process *c_p)
/* Synthesized to avoid having to generate code for it. */
c_p->def_arg_reg[0] = exception_tag[GET_EXC_CLASS(c_p->freason)];
- c_p->msg.saved_last = 0; /* No longer safe to use this position */
+ ERTS_RECV_MARK_CLEAR(c_p); /* No longer safe to use this position */
hipe_find_handler(c_p);
}
@@ -544,38 +545,57 @@ Eterm hipe_check_get_msg(Process *c_p)
msgp = PEEK_MESSAGE(c_p);
if (!msgp) {
- erts_proc_lock(c_p, ERTS_PROC_LOCKS_MSG_RECEIVE);
- /* Make sure messages wont pass exit signals... */
- if (ERTS_PROC_PENDING_EXIT(c_p)) {
- erts_proc_unlock(c_p, ERTS_PROC_LOCKS_MSG_RECEIVE);
- return THE_NON_VALUE; /* Will be rescheduled for exit */
- }
- ERTS_MSGQ_MV_INQ2PRIVQ(c_p);
- msgp = PEEK_MESSAGE(c_p);
- if (msgp)
- erts_proc_unlock(c_p, ERTS_PROC_LOCKS_MSG_RECEIVE);
- else {
- /* XXX: BEAM doesn't need this */
- c_p->hipe_smp.have_receive_locks = 1;
- c_p->flags &= ~F_DELAY_GC;
- return THE_NON_VALUE;
- }
+ int get_out;
+ (void) erts_proc_sig_receive_helper(c_p, CONTEXT_REDS, 0,
+ &msgp, &get_out);
+ /* FIXME: Need to bump reductions... */
+ if (!msgp) {
+ if (get_out) {
+ if (get_out < 0) {
+ /*
+ * FIXME: We should get out yielding
+ * here...
+ */
+ goto next_message;
+ }
+ /* Go exit... */
+ return THE_NON_VALUE;
+ }
+
+ /*
+ * If there are no more messages in queue
+ * (and we are not yielding or exiting)
+ * erts_proc_sig_receive_helper()
+ * returns with message queue lock locked...
+ */
+
+ /* XXX: BEAM doesn't need this */
+ c_p->hipe_smp.have_receive_locks = 1;
+ c_p->flags &= ~F_DELAY_GC;
+ return THE_NON_VALUE;
+ }
}
- if (is_non_value(ERL_MESSAGE_TERM(msgp))
- && !erts_decode_dist_message(c_p, ERTS_PROC_LOCK_MAIN, msgp, 0)) {
- /*
- * A corrupt distribution message that we weren't able to decode;
- * remove it...
- */
- ASSERT(!msgp->data.attached);
- UNLINK_MESSAGE(c_p, msgp);
- msgp->next = NULL;
- erts_cleanup_messages(msgp);
- goto next_message;
+ ASSERT(msgp == PEEK_MESSAGE(c_p));
+ ASSERT(msgp && ERTS_SIG_IS_MSG(msgp));
+
+ if (ERTS_SIG_IS_EXTERNAL_MSG(msgp)) {
+ /* FIXME: bump appropriate amount... */
+ if (!erts_decode_dist_message(c_p, ERTS_PROC_LOCK_MAIN, msgp, 0)) {
+ /*
+ * A corrupt distribution message that we weren't able to decode;
+ * remove it...
+ */
+ /* TODO: Add DTrace probe for this bad message situation? */
+ UNLINK_MESSAGE(c_p, msgp);
+ msgp->next = NULL;
+ erts_cleanup_messages(msgp);
+ goto next_message;
+ }
}
- ASSERT(is_value(ERL_MESSAGE_TERM(msgp)));
+ ASSERT(msgp == PEEK_MESSAGE(c_p));
+ ASSERT(ERTS_SIG_IS_INTERNAL_MSG(msgp));
return ERL_MESSAGE_TERM(msgp);
}