Merge branch 'concurrent-check-gap' into 'v9-minor'

add gap limit checks to syncstoreFinishSync

See merge request integer/scip!3515

CHANGELOG

@@ -6,6 +6,10 @@
 Features
 --------
 
+- added check for absolute and relative gap limits at end of synchronization in concurrent solving mode, in order to terminate earlier;
+  note that if the concurrent solve is stopped due to a gap limit, the "winner" solver will have an interrupted solution status and
+  its primal and dual bounds may not be the best possible ones (use SCIPgetConcurrentPrimalbound() and SCIPgetConcurrentDualbound() instead)
+
 Performance improvements
 ------------------------
 

src/scip/struct_syncstore.h

@@ -57,6 +57,8 @@ struct SCIP_SyncStore
                                               *   by all threads */
 
    SCIP*                 mainscip;           /**< the SCIP instance that was used for initializing the syncstore */
+   SCIP_Real             limit_gap;          /**< relative gap limit in main SCIP */
+   SCIP_Real             limit_absgap;       /**< absolute gap limit in main SCIP */
    SCIP_Bool             stopped;            /**< flag to indicate if the solving is stopped */
    SCIP_LOCK*            lock;               /**< lock to protect the syncstore data structure from data races */
 

src/scip/syncstore.c

@@ -148,6 +148,8 @@ SCIP_RETCODE SCIPsyncstoreInit(
    syncstore = SCIPgetSyncstore(scip);
    assert(syncstore != NULL);
    syncstore->mainscip = scip;
+   SCIP_CALL( SCIPgetRealParam(scip, "limits/gap", &syncstore->limit_gap) );
+   SCIP_CALL( SCIPgetRealParam(scip, "limits/absgap", &syncstore->limit_absgap) );
    syncstore->lastsync = NULL;
    syncstore->nsolvers = SCIPgetNConcurrentSolvers(scip);
 
@@ -492,7 +494,9 @@ SCIP_RETCODE SCIPsyncstoreFinishSync(
 
    if( (*syncdata)->syncedcount == syncstore->nsolvers )
    {
-      if( (*syncdata)->status != SCIP_STATUS_UNKNOWN )
+      if( (*syncdata)->status != SCIP_STATUS_UNKNOWN ||
+         (SCIPgetConcurrentGap(syncstore->mainscip) <= syncstore->limit_gap) ||
+         (SCIPgetConcurrentPrimalbound(syncstore->mainscip) - SCIPgetConcurrentDualbound(syncstore->mainscip) <= syncstore->limit_absgap) )
          SCIPsyncstoreSetSolveIsStopped(syncstore, TRUE);
 
       syncstore->lastsync = *syncdata;