How to generate log properly in Parallel execution

Make sure instance of every test case is different.Thats how logs will be generated separately for every test.

But still the different test case instances will execute in parallel. So all the instances will access one log file. So the report will not generate properly for each test case. Am i right?

Ex:

TC1 instance execute this line log.debug("---- TC1 ------")

TC1 instance execute this line log.debug("---- TC1 Step1 ------")

TC1 instance execute this line log.debug("---- TC1 Step2 ------")

TC2 instance execute line log.debug("---- TC2 ------")

TC2 instance  execute this line log.debug("---- TC2 Step1 ------")

TC2 instance execute this line log.debug("---- TC2 Step2 ------")

In the log file the expected output in paralllel execution should be

---- TC1 ------

---- TC1 Step1 ------

---- TC1 Step2 ------

---- TC2 ------

---- TC2 Step1 ------

---- TC2 Step2 ------

But the actual output may be

---- TC1 ------

---- TC2 ------

---- TC2 Step1 ------

---- TC1 Step1 ------

---- TC1 Step2 ------

---- TC2 Step2 ------

Anyway to resolve this?

In this case keep a separate log file for every test