Protect concurrent accesses to shared variables in process.

diff --git a/BUGS b/BUGS
index d3134734312ef918445c20e951b654484a0492ef..632bdde57d2845916a35c60e149fad9090354665 100644 (file)
--- a/BUGS
+++ b/BUGS
@@ -3,6 +3,9 @@ Les variables globales process::total_load_* ne sont pas protégées
 contre les accès concurrents.  Il n'est donc pas possible actuellement
 d'exécuter les simulations en parallèle (--cfg=contexts/nthreads).
 
+Corrigé en partie.  Il reste quelques "fixme: get locked?" à régler
+(ou pas).
+
 ========================================================================
 ##### RESOLVED BUGS COME AFTER THIS ####################################
 ========================================================================

diff --git a/main.cpp b/main.cpp
index 8a1d5c8408f74812a78f0e079eb913bfe33b13a4..f31e847d13244248afeccc28aef47a5b00c17510 100644 (file)
--- a/main.cpp
+++ b/main.cpp
@@ -274,6 +274,7 @@ int main(int argc, char* argv[])
 
     proc_mutex = new mutex_t();
     proc_cond = new condition_t();
+    process::set_proc_mutex(proc_mutex);
 
     // Launch the MSG simulation.
     XBT_INFO("Starting simulation at %f...", MSG_get_clock());
@@ -281,6 +282,7 @@ int main(int argc, char* argv[])
     simulated_time = MSG_get_clock();
     XBT_INFO("Simulation ended at %f.", simulated_time);
 
+    process::set_proc_mutex(NULL);
     delete proc_cond;
     delete proc_mutex;
 

diff --git a/process.cpp b/process.cpp
index c85b6051a6a4224452f22ddce086740f310ed61e..36bdff07cfbe8d18bf4eaf1b81d5f0cfa6b8f064 100644 (file)
--- a/process.cpp
+++ b/process.cpp
@@ -16,6 +16,8 @@ XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(proc);
 
 #include "process.h"
 
+mutex_t *process::proc_mutex;
+
 double process::total_load_init = 0.0;
 double process::total_load_running = 0.0;
 double process::total_load_exit = 0.0;
@@ -58,22 +60,21 @@ process::process(int argc, char* argv[])
         rev_neigh.insert(std::make_pair(host, ptr));
     }
 
-    // Note: there should not be race condition with the current
-    // version of Simgrid, when updating the global variables.
-
     prev_load_broadcast = -1;   // force sending of load on first send_all()
     expected_load = real_load;
-    total_load_running += real_load;
-    total_load_init += real_load;
     received_load = 0.0;
 
     idle_duration = 0.0;
     convergence = -1.0;
 
+    proc_mutex->acquire();
     process_counter++;
+    total_load_init += real_load;
+    total_load_running += real_load;
     total_load_average = total_load_running / process_counter;
     load_diff_threshold = (opt::load_ratio_threshold +
                            opt::avg_load_ratio * total_load_average) / 100.0;
+    proc_mutex->release();
 
     ctrl_close_pending = data_close_pending = neigh.size();
     close_received = false;
@@ -103,7 +104,9 @@ process::process(int argc, char* argv[])
 process::~process()
 {
     delete lb_thread;
+    proc_mutex->acquire();
     total_load_exit += real_load;
+    proc_mutex->release();
     xbt_assert(received_load == 0.0,
                "received_load is %g, but should be 0.0 !", received_load);
     if (opt::log_rate < 0)
@@ -123,7 +126,7 @@ process::~process()
 
 double process::get_iter_deviation() const
 {
-    double average_cost = opt::comp_cost(total_load_average);
+    double average_cost = opt::comp_cost(total_load_average); // fixme: get locked?
     // Do not count idle periods
     double comp_iter_opt = acc.comp_amount / average_cost;
 /*
@@ -270,26 +273,29 @@ void process::compute_loop()
     }
     real_load += received_load;
     received_load = 0.0;
+    proc_mutex->acquire();
     total_load_running -= real_load;
+    proc_mutex->release();
     convergence_check();
     comm.data_flush(true);
 }
 
 void process::convergence_check()
 {
-    double load_diff = std::fabs(real_load - total_load_average);
+    double average = total_load_average; // fixme: get locked?
+    double load_diff = std::fabs(real_load - average);
     bool converged = load_diff <= load_diff_threshold;
 
     if (convergence >= 0.0) {
         if (!converged) {
             XBT_VERB("current load has diverged: %g (%.4g%%)",
-                     real_load, 100.0 * load_diff / total_load_average);
+                     real_load, 100.0 * load_diff / average);
             convergence = -1.0;
         }
     } else {
         if (converged) {
             XBT_VERB("current load has converged: %g (%.4g%%)",
-                     real_load,  100.0 * load_diff / total_load_average);
+                     real_load,  100.0 * load_diff / average);
             convergence = MSG_get_clock();
         }
     }
@@ -327,7 +333,7 @@ bool process::still_running()
         last_status = false;
 
     } else if (100.0 * total_load_running / total_load_init <=
-               opt::load_ratio_threshold) {
+               opt::load_ratio_threshold) { // fixme: get locked?
         // fixme: this check should be implemented with a distributed
         // algorithm, and not a shared global variable!
         XBT_VERB("No more load to balance in system.");

diff --git a/process.h b/process.h
index c31d21345ab6c05993b7be8bab5cff20ea4e1f8e..901d381fabeea8d2dc0025401d7b5966cefac9a4 100644 (file)
--- a/process.h
+++ b/process.h
@@ -25,6 +25,9 @@
 
 class process {
 public:
+    static void set_proc_mutex(mutex_t* m) { proc_mutex = m;            }
+
+    // Note: normally used with proc_mutex locked.
     static double get_total_load_init()    { return total_load_init;    }
     static double get_total_load_running() { return total_load_running; }
     static double get_total_load_exit()    { return total_load_exit;    }
@@ -83,6 +86,10 @@ protected:
                        xbt_log_category_t cat = _XBT_LOGV(default)) const;
 
 private:
+    static mutex_t *proc_mutex; // protect access to global variables
+                                // (must be set before constructing
+                                // the first object!)
+
     static double total_load_init; // sum of process loads at init
     static double total_load_running; // sum of loads while running
     static double total_load_exit; // sum of process loads at exit