public BlockingTaskExecutorBuilder keepAliveTimeMillis(long keepAliveTimeMillis) {
        checkArgument(keepAliveTimeMillis >= 0,
                      "keepAliveTimeMillis: %s (expected: >= 0)", keepAliveTimeMillis);
        this.keepAliveTimeMillis = keepAliveTimeMillis;
        return this;
    }
Sets the amount of keep alive time in seconds.
core/src/main/java/com/linecorp/armeria/common/util/BlockingTaskExecutorBuilder.java