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Do I need to synchronize when writing data to the same file using BufferedWriter and FileWriter?

I am working on WebMethods Integration Server. Inside there is a java service, which is a static java method for writing data to a log file (server.log) using BufferedWriter and FileWriter. The code of the static method is as follows:

public static void writeLogFile(String message) throws ServiceException{ try { BufferedWriter bw = new BufferedWriter(new FileWriter("./logs/server.log", true)); bw.write(message); bw.newLine(); bw.close(); } catch (Exception e) { throw new ServiceException(e.getMessage()); } }

Note:
- The code has been simplified, for example, for the purpose.
-I cannot change the declaration of the writeLogFile method and attribute. That means it will always be: public static void writeLogFile. This modification is prohibited: public synchronized void writeLogFile.

There is a possibility that the writeLogFile method may be called by different instances, so I need to make sure that there are no two or more instances to access the same resource (server.log) at the same time. This means that if there are two instances trying to access server.log, one of the instances will have to wait for another instance to complete writing data to server.log.

Questions: Should I change the code above? If so, what modification do I need to do? Should I implement “synchronized” inside a static java method?

@EJP:
So which one is the best code to implement synchronization below?

1)

  FileWriter fw = new FileWriter("./logs/server.log", true); synchronized (fw) { BufferedWriter bw = new BufferedWriter(fw); bw.write(message); bw.newLine(); bw.close(); }

2)

  BufferedWriter bw = new BufferedWriter(new FileWriter("./logs/server.log", true)); synchronized(bw) { bw.write(message); bw.newLine(); bw.close(); }

3)

  synchronized(util.class) { //yes, the class name is started with lowercase BufferedWriter bw = new BufferedWriter(new FileWriter("./logs/server.log", true)); bw.write(message); bw.newLine(); bw.close(); }

4) Another opinion?

Thanks.

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3 answers

Just make the method synchronized. This does not affect its signature method for binary compatibility purposes.

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I have another suggestion. I suggest that synchronization can be seen as an aspect, and the same can be achieved using some AOP framework. This complies with the requirement not to change the code. But I'm not 100% sure, and posted a question for him. Please follow his answers.

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No. base class BufferedWriter and FileWriter are java.io.Writer,

he has his own lock for every write operation

 Object java.io.Writer.lock The object used to synchronize operations on this stream.

try making BufferedWriter bw static and ref refer to it using the static method, so the whole record is written to the file through the same Writer object

btw, I assume you are inventing still-more-log-lib ... maybe you could use log4j or any kind of lib library instead

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