Java FileWriter：客户端-服务器环境上的重复文件打开/关闭（多个实例）与单个打开/关闭（单个实例）

Question

We currently have a client-server system. We have this application that will monitor the performance of each transactions on our system (start-end time of a request/processing/sql queries...etc.) by writing the logs into a text file on the client's pc.

Our current implementation was on every request, we will open the log file, write the details of the transaction, then close the file for every request that we make. There is also a separate instance of the FileWriter for each client.

We are wondering if it is better to have the text file open all throughout the use of the application and then just close it upon log-out using a single instance of the FileWriter.

1. What are the impacts of just using a single instance of the FileWriter?
2. Would there be a significant speed change when we change the Filewriter from Multiple Instance to single instance?

Answer 1

If you are doing a lot of writing you might see a performance improvement with a single open close of the file. However, I imagine any gain would not be worth the effort as it sounds like that would be a drop in the bucket compared to other actions you are doing (sql queries especially).

Answer 2

Your platform might force you to use only one FileWriter for the same file. Keep the handle open. You should at least use a PrintWriter which handles thread-synchronization internally. Performance-wise, you can trade safety for performance by using (or not) FileDescriptor.sync(). You can create a FileWriter using a FileDescriptor , which you can get from a FileOutputStream .

I second the notion to just use log4j or Java's own logging mechanism.