diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 4baeaa2..52ac271 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -31,6 +31,7 @@
 #include "libpq/md5.h"
 #include "miscadmin.h"
 #include "storage/lmgr.h"
+#include "storage/procarray.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
@@ -1026,6 +1027,12 @@ DropRole(DropRoleStmt *stmt)
 					 errdetail_internal("%s", detail),
 					 errdetail_log("%s", detail_log)));
 
+		/* If this role is currently connecting, refuse to drop it. */
+		if (BackendRoleProcExists(roleid))
+			ereport(ERROR,
+					(errcode(ERRCODE_DEPENDENT_OBJECTS_STILL_EXIST),
+					 errmsg("role \"%s\" is currently logged in", role)));
+
 		/*
 		 * Remove the role from the pg_authid table
 		 */
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 740beb6..ad208d7 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2358,6 +2358,54 @@ BackendPidGetProcWithLock(int pid)
 }
 
 /*
+ * BackendRoleProcExists -- check if a backend with given its role exists
+ *
+ * Returns true if found.
+ */
+bool
+BackendRoleProcExists(Oid roleoid)
+{
+	bool	   result;
+
+	if (roleoid == 0)		/* No match with role id 0 */
+		return false;
+
+	LWLockAcquire(ProcArrayLock, LW_SHARED);
+
+	result = BackendRoleProcExistsWithLock(roleoid);
+
+	LWLockRelease(ProcArrayLock);
+
+	return result;
+}
+
+/*
+ * BackendRoleProcExistsWithLock -- check if a backend with given its role
+ * exists
+ *
+ * Same as above, except caller must be holding ProcArrayLock.
+ */
+bool
+BackendRoleProcExistsWithLock(Oid roleoid)
+{
+	ProcArrayStruct *arrayP = procArray;
+	int			index;
+
+	if (roleoid == 0)		/* No match with role id 0 */
+		return false;
+
+	for (index = 0; index < arrayP->numProcs; index++)
+	{
+		PGPROC	   *proc = &allProcs[arrayP->pgprocnos[index]];
+
+		if (proc->roleId == roleoid)
+			return true;
+	}
+
+	return false;
+}
+
+/*
  * BackendXidGetPid -- get a backend's pid given its XID
  *
  * Returns 0 if not found or it's a prepared transaction.  Note that
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index d13355b..f115c43 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -41,6 +41,7 @@
 #include "storage/fd.h"
 #include "storage/ipc.h"
 #include "storage/latch.h"
+#include "storage/lmgr.h"
 #include "storage/pg_shmem.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
@@ -500,20 +501,24 @@ InitializeSessionUserId(const char *rolename, Oid roleid)
 			ereport(FATAL,
 					(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 					 errmsg("role \"%s\" does not exist", rolename)));
-	}
-	else
-	{
-		roleTup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
-		if (!HeapTupleIsValid(roleTup))
-			ereport(FATAL,
-					(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
-					 errmsg("role with OID %u does not exist", roleid)));
+		roleid = HeapTupleGetOid(roleTup);
+		ReleaseSysCache(roleTup);
 	}
 
+	/*
+	 * Inhibiting this session from being activated for concurrently dropped
+	 * roles
+	 */
+	LockSharedObject(AuthIdRelationId, roleid, 0, AccessShareLock);
+
+	roleTup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
+	if (!HeapTupleIsValid(roleTup))
+		ereport(FATAL,
+				(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
+				 errmsg("role with OID %u does not exist", roleid)));
+
 	rform = (Form_pg_authid) GETSTRUCT(roleTup);
-	roleid = HeapTupleGetOid(roleTup);
 	rname = NameStr(rform->rolname);
-
 	AuthenticatedUserId = roleid;
 	AuthenticatedUserIsSuperuser = rform->rolsuper;
 
@@ -524,6 +529,8 @@ InitializeSessionUserId(const char *rolename, Oid roleid)
 	/* (We assume this is an atomic store so no lock is needed) */
 	MyProc->roleId = roleid;
 
+	UnlockSharedObject(AuthIdRelationId, roleid, 0, AccessShareLock);
+
 	/*
 	 * These next checks are not enforced when in standalone mode, so that
 	 * there is a way to recover from sillinesses like "UPDATE pg_authid SET
diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h
index dd37c0c..8c69d6f 100644
--- a/src/include/storage/procarray.h
+++ b/src/include/storage/procarray.h
@@ -62,6 +62,8 @@ extern bool HaveVirtualXIDsDelayingChkpt(VirtualTransactionId *vxids, int nvxids
 
 extern PGPROC *BackendPidGetProc(int pid);
 extern PGPROC *BackendPidGetProcWithLock(int pid);
+extern bool	   BackendRoleProcExists(Oid roleoid);
+extern bool	   BackendRoleProcExistsWithLock(Oid roleoid);
 extern int	BackendXidGetPid(TransactionId xid);
 extern bool IsBackendPid(int pid);