版本

mysql:mysql-connector-java:8.0.30

现象

使用流式处理，处理过程中希望中断，关闭流却无响应

原因

mysql需要将流式查询中的所有记录全部读取才能关闭流
中断时剩余的记录数量过多，遍历时间长导致假死现象

源码

com.mysql.cj.protocol.a.result.ResultsetRowsStreaming

// 关闭流
public void close() {
    
    
    Object mutex = this.owner != null && this.owner.getSyncMutex() != null ? this.owner.getSyncMutex() : this;

    boolean hadMore = false;
    int howMuchMore = 0;

    synchronized (mutex) {
    
    
        // 读取剩余的所有记录
        while (next() != null) {
    
    
            hadMore = true;
            howMuchMore++;

            if (howMuchMore % 100 == 0) {
    
    
                Thread.yield();
            }
        }

        if (!this.protocol.getPropertySet().getBooleanProperty(PropertyKey.clobberStreamingResults).getValue()
                && this.protocol.getPropertySet().getIntegerProperty(PropertyKey.netTimeoutForStreamingResults).getValue() > 0) {
    
    
            int oldValue = this.protocol.getServerSession().getServerVariable("net_write_timeout", 60);

            this.protocol.clearInputStream();

            try {
    
    
                this.protocol.sendCommand(this.commandBuilder.buildComQuery(this.protocol.getSharedSendPacket(), "SET net_write_timeout=" + oldValue,
                        this.protocol.getPropertySet().getStringProperty(PropertyKey.characterEncoding).getValue()), false, 0);
            } catch (Exception ex) {
    
    
                throw ExceptionFactory.createException(ex.getMessage(), ex, this.exceptionInterceptor);
            }
        }

        if (this.protocol.getPropertySet().getBooleanProperty(PropertyKey.useUsageAdvisor).getValue()) {
    
    
            if (hadMore) {
    
    
                this.owner.getSession().getProfilerEventHandler().processEvent(ProfilerEvent.TYPE_USAGE, this.owner.getSession(),
                        this.owner.getOwningQuery(), null, 0, new Throwable(),
                        Messages.getString("RowDataDynamic.1", new String[] {
    
     String.valueOf(howMuchMore), this.owner.getPointOfOrigin() }));
            }
        }
    }

    this.metadata = null;
    this.owner = null;
}