HI Team Our codebase is in Kotlin and we are using OpenTraci

Question

HI Team Our codebase is in Kotlin and we are using OpenTracing library for distributed tracing We have implemented our custom `ThreadContextElement` as described in the documentation The problem is we are having memory leak heap dump shows that opentracing lib objects being leaked when we use different dispatchers in the flow For example in the beginning of the process Step 1 gt `rxCompletable default dispatcher` Step 2 gt Use another dispatcher for a network call `withContext + CustomThreadContextElement ` ^^ when we switch dispatcher like this we always get memory leak As long as the entire flow is on one dispatcher we don t get memory leak Any thoughts here I am also seeing this should we be using this I am not clear on the example provided in the documentation especially the line ```return CopyForChildCoroutineElement traceThreadLocal get ``` Where is this `CopyForChildCoroutineElement` class is from

Oliver.O · Answer

No idea what might be causing your memory leak but you d use `CopyableThreadContextElement` for a coroutine local context The documentation you were seeing is inaccurate Here is a PR with a fix merged not yet released <https github com Kotlin kotlinx coroutines pull 3157 files>

Oliver.O · Answer

Another example using `CopyableThreadContextElement` <https github com kotest kotest blob master kotest assertions kotest assertions shared src jvmMain kotlin io kotest assertions ErrorCollector kt>

seetha · Answer

< Oliver O> Thank you for clarifying on CopyableThreadContextElement and the examples Reading more about this on different issue particularly this PR Do you think this could be our problem Meaning we might have to set the ThreadLocal involved in our use case to NULL at the main dispatcher before we switch to different dispatcher so that when the context moves out to main `restoreThreadContext` gets called

Oliver.O · Answer

The PR you are referring to has been merged so my understanding is that `ThreadContextElement` is always restored properly I doubt that it is possible to give some generic advice in a multithreading scenario like this but things you might want to look at referring to the include Is your `ThreadLocal` initialized and inserted into the initial coroutine context before using it for the first time e g via as in `withContext threadLocal asContextElement value = launch ` Is your `ThreadLocal` mutated once set If your `ThreadLocal` points to a mutable box is the latter thread safe Is your `ThreadLocal` used exclusively within coroutines including code called from a coroutine Is your `ThreadContextElement` present in every coroutine context Do you use to check this