摘要：

我们在Spring-Boot 2.0.4和存在一个主要的性能问题Couchbase server 5.5.1

随着线程数量的增加，数据库响应时间性能迅速下降。这是有关该问题的另一份报告。

详细信息：

Spring Boot正在运行500个线程：

server:
  tomcat:
    max-threads: 500
    max-connections: 500

我们使用以下依赖项：

     <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-couchbase</artifactId>
        <version>3.0.9.RELEASE</version>
    </dependency>

我们从DB的“选择”是通过Spring-Data存储库执行的：

Cat findFirstByOwnerIdAndNameAndColor(String ownerId, String name, String color);

我们有一个特别适合此查询的索引：

CREATE INDEX `cat_by_ownerId_name_and_color_idx` ON `pets`(`ownerId`,`name`,`color`) WHERE (`_class` = "com.example.Cat")

随着请求数量的增加，我们可以看到数据库回答查询的时间迅速减少。

例如，当每秒运行300个请求时，响应时间的99％约为 10秒！ 而50的百分位数约为5秒。

返回的文档的平均大小约为 300字节 。这意味着我们正在尝试每秒提取大约90千字节。相对较低的数量。

编辑：

我在此处添加在Couchbase的UI中运行相同查询的结果：（在UI中，查询需要1.75毫秒才能完成）。

{
 "plan": {
  "#operator": "Sequence",
  "~children": [
  {
    "#operator": "IndexScan3",
    "index": "cats_by_ownerId_name_and_color_idx",
    "index_id": "c061141c2d373067",
    "index_projection": {
      "primary_key": true
    },
    "keyspace": "pets",
    "namespace": "default",
    "spans": [
      {
        "exact": true,
        "range": [
          {
            "high": "\"bf23fa4c-22c3-42ac-b141-39cdc76bb2x5\"",
            "inclusion": 3,
            "low": "\"bf23fa4c-22c3-42ac-b141-39cdc76bb2x5\""
          },
          {
            "high": "\"Oscar\"",
            "inclusion": 3,
            "low": "\"Oscar\""
          },
          {
            "high": "\"red\"",
            "inclusion": 3,
            "low": "\"red\""
          }
        ]
      }
    ],
    "using": "gsi"
  },
  {
    "#operator": "Fetch",
    "keyspace": "pets",
    "namespace": "default"
  },
  {
    "#operator": "Parallel",
    "~child": {
      "#operator": "Sequence",
      "~children": [
        {
          "#operator": "Filter",
          "condition": "(((((`pets`.`_class`) = \"com.example.Cat\") and ((`pets`.`ownerId`) = \"bf23fa4c-22c3-42ac-b141-39cdc76bb2x5\")) and ((`pets`.`name`) = \"Oscar\")) and ((`pets`.`color`) = \"red\"))"
        },
        {
          "#operator": "InitialProject",
          "result_terms": [
            {
              "expr": "self",
              "star": true
            }
          ]
        },
        {
          "#operator": "FinalProject"
        }
      ]
    }
  }
]
 },
 "text": "select * from pets where _class=\"com.example.Cat\" and projectId=\"bf23fa4c-22c3-42ac-b141-39cdc76bb2x5\" and name=\"Oscar\" and color=\"red\""

}

编辑2

我们还尝试隐式编写N1ql查询，但结果是相同的。和以前一样，我们获得了许多TimeOutExceptions：

   Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.QueryTimeoutException: java.util.concurrent.TimeoutException: {"b":"pets","s":"n1ql","t":7500000,"i":"f8cdf670-d32a-4d74-858c-f9dd9789d264"}; nested exception is java.lang.RuntimeException: java.util.concurrent.TimeoutException: {"b":"pets","s":"n1ql","t":7500000,"i":"f8cdf670-d32a-4d74-858c-f9dd9789d264"}] with root cause

java.util.concurrent.TimeoutException: {"b":"pets","s":"n1ql","t":7500000,"i":"f8cdf670-d32a-4d74-858c-f9dd9789d264"}
   at com.couchbase.client.java.bucket.api.Utils$1.call(Utils.java:131) ~[java-client-2.7.0.jar:na]
   at com.couchbase.client.java.bucket.api.Utils$1.call(Utils.java:127) ~[java-client-2.7.0.jar:na]
   at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:140) ~[rxjava-1.3.8.jar:1.3.8]
   at rx.internal.operators.OnSubscribeTimeoutTimedWithFallback$TimeoutMainSubscriber.onTimeout(OnSubscribeTimeoutTimedWithFallback.java:166) ~[rxjava-1.3.8.jar:1.3.8]
   at rx.internal.operators.OnSubscribeTimeoutTimedWithFallback$TimeoutMainSubscriber$TimeoutTask.call(OnSubscribeTimeoutTimedWithFallback.java:191) ~[rxjava-1.3.8.jar:1.3.8]
   at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55) ~[rxjava-1.3.8.jar:1.3.8]
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[na:1.8.0_161]
   at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_161]
   at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) ~[na:1.8.0_161]
   at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) ~[na:1.8.0_161]
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) ~[na:1.8.0_161]
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) ~[na:1.8.0_161]
   at java.lang.Thread.run(Thread.java:748) [na:1.8.0_161]

有没有办法解决这个问题，或者我们需要一个不同的数据库？