springboot druid数据库连接池连接失败后一直重连的解决方法-亚博电竞手机版

目录

• druid 重连原因
• errorcount 错误次数
• 总结

在使用个人阿里云测试机，在查询实时输出日志时，看到数据库连接失败后，服务器一直在重连服务器。开始以为是遭受重复攻击，后面把服务重启后，就没有出现一直重连的情况。看以下输出日志：

2022-02-09 11:04:58.896 error 16876 --- [eate-1550991149] com.alibaba.druid.pool.druiddatasource : create connection sqlexception, url: jdbc:mysql://47.98.67,98:1234/test?usessl=false&characterencoding=utf-8&servertimezone=utc, errorcode 1045, state 28000

java.sql.sqlexception: access denied for user 'root'@'113.90.123.76' (using password: yes)

at com.mysql.cj.jdbc.exceptions.sqlerror.createsqlexception(sqlerror.java:129) ~[mysql-connector-java-8.0.16.jar:8.0.16]

at com.mysql.cj.jdbc.exceptions.sqlerror.createsqlexception(sqlerror.java:97) ~[mysql-connector-java-8.0.16.jar:8.0.16]

at com.mysql.cj.jdbc.exceptions.sqlexceptionsmapping.translateexception(sqlexceptionsmapping.java:122) ~[mysql-connector-java-8.0.16.jar:8.0.16]

at com.mysql.cj.jdbc.connectionimpl.createnewio(connectionimpl.java:835) ~[mysql-connector-java-8.0.16.jar:8.0.16]

at com.mysql.cj.jdbc.connectionimpl.(connectionimpl.java:455) ~[mysql-connector-java-8.0.16.jar:8.0.16]

at com.mysql.cj.jdbc.connectionimpl.getinstance(connectionimpl.java:240) ~[mysql-connector-java-8.0.16.jar:8.0.16]

at com.mysql.cj.jdbc.nonregisteringdriver.connect(nonregisteringdriver.java:199) ~[mysql-connector-java-8.0.16.jar:8.0.16]

at com.alibaba.druid.filter.filterchainimpl.connection_connect(filterchainimpl.java:156) ~[druid-1.1.10.jar:1.1.10]

at com.alibaba.dhttp://www.cppcns.comruid.filter.stat.statfilter.connection_connect(statfilter.java:218) ~[druid-1.1.10.jar:1.1.10]

at com.alibaba.druid.filter.filterchainimpl.connection_connect(filterchainimpl.java:150) ~[druid-1.1.10.jar:1.1.10]

at com.alibaba.druid.pool.druidabstractdatasource.createphysicalconnection(druidabstractdatasource.java:1560) ~[druid-1.1.10.jar:1.1.10]

at com.alibaba.druid.pool.druidabstractdatasource.createphysicalconnection(druidabstractdatasource.java:1623) ~[druid-1.1.10.jar:1.1.10]

at com.alibaba.druid.pool.druiddatasource$createconnectionthread.run(druiddatasource.java:2468) ~[druid-1.1.10.jar:1.1.10]

注意上面一直有 druid 数据库连接池的提示，这里就想到可能是 druid 连接池的问题，然后去掉 druid maven 依赖后在请求接口就不会出现重连的问题。

druid 重连原因

在上图源码找到最后一行 druiddatasource.java:2468 定位到源码上，createconnectionthread 创建连接线程，看一下 createconnectionthread 源码：

public class createconnectionthread extends thread { public createconnectionthread(string name){ super(name); this.setdaemon(true); } public void run() { initedlatch.countdown(); long lastdiscardcount = 0; int errorcount = 0; for (;;) { // addlast try { lock.lockinterruptibly(); } catch (interruptedexception e2) { break; } long discardcount = druiddatasource.this.discardcount; boolean discardchanged = discardcount - lastdiscardcount > 0; lastdiscardcount = discardcount; try { boolean emptywait = true; if (createerror != null && poolingcount == 0 && !discardchanged) { emptywait = false; } if (emptywait && asyncinit && createcount < initialsize) { emptywait = false; } if (emptywait) { // 必须存在线程等待，才创建连接 if (poolingcount >= notemptywaitthreadcount // && !(keepalive && activecount poolingcount < minidle)) { empty.await(); } // 防止创建超过maxactive数量的连接 if (activecount poolingcount >= maxactive) { empty.await(); continue; } } } catch (interruptedexception e) { lastcreateerror = e; lasterrortimemillis = system.currenttimemillis(); if (!closing) { log.error("create connection thread interrupted, url: " jdbcurl, e); } break; } finally { lock.unlock(); } physicalconnectioninfo connection = null; try { connection = createphysicalconnection(); setfailcontinuous(false); } catch (sqlexception e) { log.error("create connection sqlexception, url: " jdbcurl ", errorcode " e.geterrorcode() ", state " e.getsqlstate(), e); errorcount ; if (errorcount > connectionerrorretryattempts && timebetweenconnecterrormillis > 0) { // fail over retry attempts setfailcontinuous(true); if (failfast) { lock.lock(); try { notempty.signalall(); } finally { lock.unlock(); } } if (breakafteracquirefailure) { break; } try { thread.sleep(timebetweenconnecterrormillis); } catch (interruptedexception interruptex) { break; } } } catch (runtimeexception e) { log.error("create connection runtimeexception", e); setfailcontinuous(true); continue; } catch (error e) { log.error("create connection error", e); setfailcontinuous(true); break; } if (connection == null) { continue; } boolean result = put(connection); if (!result) { jdbcutils.close(connection.getphysicalconnection()); log.info("put physical connection to pool failed."); } errorcount = 0; // reset errorcount } } }

这是一个多线程的类，而 run 方法里面设置了没有限制的 for 循环 for (;;) {}, 而日志报错定位的信息:

connection = createphysicalconnection();

如果符合条件 errorcount > connectionerrorretryattempts && timebetweenconnecterrormillis > 0 会再次尝试重连，先看一下这几个参数的含义：

errorcount 错误次数

在 run 方法初始化时为零，每次连接失败，会自动加1

connectionerrorretryattempts

连接错误重试次数，默认值为 1。

protected int connectionerrorretryattempts = 1;

timebetweenconnecterrormillis

连接间隔时间，单位毫秒。默认值为 500。

protected volatile long timebetweenconnecterrormillis = default_time_between_connect_error_millis; public static final long default_time_between_connect_error_millis = 500;

我们在连接数据库失败后，要不在里面 break 中断，其中有

if (breakafteracquirefailure) { break; }

将改 break-after-acquire-failure 设置成 true,在 application.properties 文件如下配置：

spring.datasource.druid.break-after-acquire-failure=true

如果想多尝试连接几次，需要设置 connection-error-retry-attempts ,当 errorcount 大于 connectionerrorretryattempts 才会进入到 条件内，才会中断循环。在 application.properties 文件如下配置：

spring.datasource.druid.connection-error-retry-attempts=3

总结

druid 数据库连接失败，是因为在使用多线程连接数据时使用了无限制循环连接，需要在连接失败中断连接，需要设置 break-after-acquire-failure 为 true。设置之后数据库连接不成功也不会不断的重试。如果要设置重连次数要设置 connection-error-retry-attempts。

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