From 124a402ade3fd37e1e3218c1bce6c463c48e5886 Mon Sep 17 00:00:00 2001
From: virusdefender <1670873886@qq.com>
Date: Tue, 8 Dec 2015 14:51:50 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=E7=AB=9E=E6=80=81=E6=9D=A1?=
 =?UTF-8?q?=E4=BB=B6=E5=AF=BC=E8=87=B4=E7=9A=84=E8=AE=A1=E6=95=B0=E5=99=A8?=
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---
 judge_dispatcher/models.py | 20 ++++++++++++--------
 judge_dispatcher/tasks.py  | 27 +++++++++++++++------------
 2 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/judge_dispatcher/models.py b/judge_dispatcher/models.py
index 4e75bca9..6b2a4dee 100644
--- a/judge_dispatcher/models.py
+++ b/judge_dispatcher/models.py
@@ -16,16 +16,20 @@ class JudgeServer(models.Model):
     status = models.BooleanField(default=True)
 
     def use_judge_instance(self):
-        self.left_instance_number -= 1
-        self.workload = 100 - int(float(self.left_instance_number) / self.max_instance_number * 100)
-        print self.left_instance_number, self.workload
-        self.save()
+        # 因为use 和 release 中间是判题时间，可能这个 model 的数据已经被修改了，所以不能直接使用self.xxx，否则取到的是旧数据
+        server = JudgeServer.objects.select_for_update().get(id=self.id)
+        server.left_instance_number -= 1
+        server.workload = 100 - int(float(server.left_instance_number) / server.max_instance_number * 100)
+        print "\n ---- use", server.left_instance_number, server.workload
+        server.save()
 
     def release_judge_instance(self):
-        self.left_instance_number += 1
-        self.workload = 100 - int(float(self.left_instance_number) / self.max_instance_number * 100)
-        print self.left_instance_number, self.workload
-        self.save()
+        # 使用原子操作
+        server = JudgeServer.objects.select_for_update().get(id=self.id)
+        server.left_instance_number += 1
+        server.workload = 100 - int(float(server.left_instance_number) / server.max_instance_number * 100)
+        print "\n ---- release", server.left_instance_number, server.workload
+        server.save()
 
     class Meta:
         db_table = "judge_server"
diff --git a/judge_dispatcher/tasks.py b/judge_dispatcher/tasks.py
index 38d9ef1f..c487eefa 100644
--- a/judge_dispatcher/tasks.py
+++ b/judge_dispatcher/tasks.py
@@ -26,31 +26,32 @@ class JudgeDispatcher(object):
         self.memory_limit = memory_limit
         self.test_case_id = test_case_id
         self.user = User.objects.get(id=submission.user_id)
+        print "init init"
 
     def choose_judge_server(self):
         servers = JudgeServer.objects.filter(workload__lt=100, lock=False, status=True).order_by("-workload")
         if servers.exists():
-            server = servers[0]
-            server.use_judge_instance()
-            return server
+            return servers.first()
 
     def judge(self, is_waiting_task=False):
         self.submission.judge_start_time = int(time.time() * 1000)
-        try:
-            judge_server = self.choose_judge_server()
-            # 如果没有合适的判题服务器，就放入等待队列中等待判题
-            if not judge_server:
-                if not is_waiting_task:
-                    JudgeWaitingQueue.objects.create(submission_id=self.submission.id, time_limit=self.time_limit,
-                                                     memory_limit=self.memory_limit, test_case_id=self.test_case_id)
-                return
+        judge_server = self.choose_judge_server()
 
+        # 如果没有合适的判题服务器，就放入等待队列中等待判题
+        if not judge_server:
+            if not is_waiting_task:
+                JudgeWaitingQueue.objects.create(submission_id=self.submission.id, time_limit=self.time_limit,
+                                                 memory_limit=self.memory_limit, test_case_id=self.test_case_id)
+            return
+
+        judge_server.use_judge_instance()
+
+        try:
             s = TimeoutServerProxy("http://" + judge_server.ip + ":" + str(judge_server.port), timeout=20)
 
             data = s.run(judge_server.token, self.submission.id, self.submission.language,
                          self.submission.code, self.time_limit, self.memory_limit, self.test_case_id)
 
-            judge_server.release_judge_instance()
             # 编译错误
             if data["code"] == 1:
                 self.submission.result = result["compile_error"]
@@ -67,6 +68,8 @@ class JudgeDispatcher(object):
             self.submission.result = result["system_error"]
             self.submission.info = str(e)
         finally:
+            judge_server.release_judge_instance()
+
             self.submission.judge_end_time = int(time.time() * 1000)
             self.submission.save()