It will help you with many different low-level issues including storage management, platform means dependencies, and so forth.

Tuesday, November 30th 2021.

It will help you with many different low-level issues including storage management, platform means dependencies, and so forth.

Nonetheless we nevertheless often have crashes with OutOfMemory. Very wheres the rubbish enthusiast?

Im planning to pay attention to one of many instances when huge items in storage cant feel cleared for a lengthy time frame. This case is not in the end a memory leak things shall be accumulated at some point so we sometimes dismiss it. It is not recommended because it can occasionally trigger OOM errors.

Possible Im explaining could be the Handler leak, that is normally identified as a warning by Lint.

Fundamental Example

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This will be a really standard activity. Notice that this anonymous Runnable happens to be submitted into the Handler with a long wait. Well operate it and turn the telephone handful of circumstances, next dispose of memory space and assess it.

There is seven activities in storage now. It is definitely not good. Lets know precisely why GC is not able to clean them.

The query we built to see a summary of all strategies leftover in memory space is made in OQL (item Query words), and that is quite simple, yet effective.

Perhaps you have realized, the strategies is actually referenced by this$0 . This is certainly an indirect resource through the unknown course on owner course. This$0 try referenced by callback , that is after that referenced by a chain of subsequent s of content back once again to the main thread.

If you make a non-static course within the manager class, Java creates an indirect mention of the owner

When you publish Runnable or Message into Handler , it’s next kept in selection of information commands referenced from LooperThread till the information try accomplished. Posting delayed communications was a definite leak for at least enough time regarding the wait price. Publishing immediately may cause a temporary drip also if the queue of information is huge.

Fixed Runnable Solution

Lets try to conquer a mind drip through getting reduce this$0 , by converting the unknown lessons to static.

Operate, rotate and obtain the memory dump.

Just what, again? Lets see whom helps to keep making reference to strategies .

Read the bottom of the forest activity is actually kept as a mention of mContext inside mTextView your DoneRunnable course. Making use of static internal courses is certainly not enough to mastered memory space leakage, nonetheless. We have to would extra.

Static Runnable With WeakReference

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Lets keep using iterative fixes and get eliminate the regard to TextView, which keeps task from getting destroyed.

Remember that we’re keeping WeakReference to TextView, and lets run, turn and dump memory.

Be cautious with WeakReferences. They may be null at any minute, very solve them first to an area adjustable (difficult research) following scan to null before utilize.

Hooray! Singular activity instance. This solves our very own storage complications.

So with this means we should:

  • Need static inner courses (or outside tuition)
  • Use WeakReference to all or any objects controlled from Handler / Runnable

In the event that you evaluate this rule to your initial laws, you might find a huge difference in readability and laws clearance. The original signal is much shorter and much crisper, and youll note that sooner or later, book in textView are changed to Done. No reason to see the signal to realise that.

Creating this much boilerplate laws is really tiresome, particularly if postDelayed is set to a few days, such as for example 50ms. There are much better and sharper assistance.

Washing All Communications onDestroy

Handler course possess a fascinating ability removeCallbacksAndMessages – which can take null as argument. It will probably remove all Runnables and information posted to some handler. Lets put it to use in onDestroy .

Lets run, rotate and dump memories.

Good! Only one instance.

This process is actually a lot better compared to past one, because helps to keep code clear and clear. The only real expense is always to don’t forget to clear all information on activity / fragment kill.

I’ve an additional option which, if youre lazy just like me, you could including much more. 🙂

Utilize WeakHandler

The Badoo team created the fascinating notion of adding WeakHandler – a course that acts as Handler , it is way much safer.

It requires advantage of hard and weakened records to remove mind leakages. I am going to describe the idea at length slightly after, but lets go through the rule 1st:

Much like the initial rule in addition to one lightweight huge difference rather than making use of android.os.Handler , Ive made use of WeakHandler . Lets run, turn and dispose of mind:

Kind, is not they? The laws was cleaner than ever before, and memory is thoroughly clean also! 🙂

To utilize it, only create dependency your build.gradle:

And import they inside coffee course:

Go to Badoos github webpage, where you are able to fork they, or learn its source laws

WeakHandler. The way it operates

The primary aim of WeakHandler would be to hold Runnables / emails hard-referenced while WeakHandler is hard-referenced. As soon as it may be GC-ed, all information should go out besides.

Is a simple drawing that displays differences when considering making use of typical Handler and WeakHandler to post unknown runnables:

Taking a look at the top drawing, Activity keeps a reference to Handler , which posts Runnable Age Gap dating (throws they into queue of information referenced from Thread). All things are good except the secondary guide from Runnable to Activity . While content is in the waiting line, all graphs cant become garbage-collected.

In contrast, inside bottom diagram task keeps WeakHandler , which will keep Handler inside. Whenever we inquire it to share Runnable , it is covered into WeakRunnable and uploaded. And so the information queue keeps guide simply to WeakRunnable . WeakRunnable keeps weakened mention of the desired Runnable , so that the Runnable are garbage-collected.

Another small key would be that WeakHandler still helps to keep a hard mention of the the required Runnable , avoiding it from getting garbage-collected while WeakRunnable try energetic.

The side-effect of using WeakHandler usually all messages and runnables is almost certainly not accomplished if WeakHandler is garbage-collected. To stop that, merely keep a reference to it from Activity. Once task is ready to feel obtained, all graphs with WeakHandler will gathered nicely.


Utilizing postDelayed in Android os requires additional energy. To experience it we developed three different methods:

  • Make use of a fixed interior Runnable / Handler with WeakReference to owner lessons
  • Evident all information from Handler in onDestroy of task / Fragment
  • Need WeakHandler from Badoo as a silver bullet

it is for you to decide to decide on your favorite approach. The next appears very reasonable, but requires some extra services. The next try my personal favorite, demonstrably, however it call for some interest nicely WeakHandler should not be used without difficult reference from outdoors. And many thanks for scanning!

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Related Article It will help you with many different low-level issues including storage management, platform means dependencies, and so forth.