Unusual memory consumption in working with fragments

Question

I have a method in my program which I create a new fragment and start that fragment in it. But we have several Out Of Memory crashes in our app, So I decided to look at the memory profiler of the android studio and this is the result of opening several fragments with this piece of code:

public void openFragment(MyCustomFragment fragment, boolean isDialog,
                         FragmentAnimationType animationType) {
    mStackCountAfterExternalIntent++;
    FragmentManager childFragmentManager = mFragmentAdapter.getItem(mActiveTab)
            .getChildFragmentManager();
    try {
        FragmentTransaction fragmentTransaction = childFragmentManager.beginTransaction();
            if (animationType != null) {
                fragmentTransaction.setCustomAnimations(animationType.enterAnimation, 0,
                        0, animationType.exitAnimation);
            }
            fragmentTransaction.replace(R.id.child_fragment_root, fragment);
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commitAllowingStateLoss();
            if (childFragmentManager.getBackStackEntryCount() > 0) {
                FragmentManager fragmentManager = mFragmentAdapter.getItem(mActiveTab)
                        .getChildFragmentManager();
                MyCustomFragment fragmentToHide = (MyCustomFragment) fragmentManager.
                        getFragments().get(fragmentManager.getBackStackEntryCount() - 1);
            }
        System.gc();
        fragment.onVisible(true);
    } catch (Exception e) {
        App.getInstance().restartApp(mLastIntent, false);
    }
}

I think this memory usage is unusual, Why the memory usage never goes down after opening a new fragment? Is this a result of memory leak? Do you have any suggestion for more investigating?

Update1:

MyCustomFragment is a fragment which extends from Android DialogFragment and also is a base for another fragments in my project, all of my fragments extends from it.

Update2:

I changed my fragments to extends from Fragment instead of MyCustomFragment and problem does not solved.

Note1:

what is mFragmentAdapter?: We have a bottom menu in project and use ViewPager and FragmentPagerAdapter for handling it and its tabs, this variable used for that.

[System.gc() isn't good practice](https://stackoverflow.com/questions/2414105/why-is-it-bad-practice-to-call-system-gc) — 2Dee, Mar 27 '18 at 09:12
Are you storing any fields in MyCustomFragment which have a context, for example any Views? they could be preventing MyCustomFragment from being GC'd — Peter, Mar 27 '18 at 09:18
@FaizanMubasher It is just a customized and general fragment that extends from DialogFragment which another fragments in my project extend from it.Actually all of my fragments in my app extend from it. Need it? — Hamidreza Sahraei, Mar 27 '18 at 09:26
What is the purpose of that (looks pretty bad) `if (childFragmentManager.getBackStackEntryCount() > 0) { FragmentManager fragmentManager = mFragmentAdapter.getItem(mActiveTab) .getChildFragmentManager(); MyCustomFragment fragmentToHide = (MyCustomFragment) fragmentManager. getFragments().get(fragmentManager.getBackStackEntryCount() - 1); } System.gc(); fragment.onVisible(true);` ? — Eselfar, Mar 27 '18 at 09:26
@2Dee Yes, it was just for test, I will remove that line, Thank u for ur attention :) — Hamidreza Sahraei, Mar 27 '18 at 09:27
@Peter Yes, there are some Fields with Type of "View", Actually they are some custom views, they cause this problem? — Hamidreza Sahraei, Mar 27 '18 at 09:29
try to instantiate standard fragments and see if this happens. If it doesn't, post your custom fragments, custom views, everything you have — payloc91, Mar 27 '18 at 09:31
Yeah it seems that you have either messed up the backstack or more likely the fragment is holding a reference of himself (directly or via another object) and can't be garbage collected — Eselfar, Mar 27 '18 at 09:32
I am really interested in seeing your implementation of mFragmentAdapter. — pablo432, Mar 27 '18 at 09:36
@HamidrezaSahraei it's a possibility and it's easy to check - just remove all the fields from your fragment and access everything with getView().findViewById() directly and see if that solves your leak. All views have Context which makes it a possibility for a leak. There are some additional common pitfalls here http://blog.nimbledroid.com/2016/05/23/memory-leaks.html — Peter, Mar 27 '18 at 09:37
@MarkoPacak I tried your suggestion, but nothing changed, I have updated the question. — Hamidreza Sahraei, Mar 27 '18 at 09:53
@HamidrezaSahraei I kind of ignored messed up backstack thing. If your implementation carelessly returns new fragment with every call to FragmentAdater#getItem, that could explain memory leaks. Also... why are you extending DialogFragment? It does not look for me like a good mix, I mean using DialogFragments + FragmentAdapter... — pablo432, Mar 27 '18 at 10:16
@Eselfar No it doesn't have any reference to itself, but would you explain about how backstack might be messed up? — Hamidreza Sahraei, Mar 27 '18 at 10:19
@pablo432 Fragment adapter is for handling bottom menu which keep standard fragments in itself, MyCustomFragment is a dialog fragment for showing fragment as dialog in tablets and normal in phones. — Hamidreza Sahraei, Mar 27 '18 at 10:21
What I meant was: instantiate plain fragments with your method and see if the error occurs again — payloc91, Mar 27 '18 at 10:37
I thought you where doing strange thing with the Fragments in the backstack but it seems ok. Can you please post your FragmentAdapter? — Eselfar, Mar 27 '18 at 10:38
How do you pass fragments to `openFragment`? Post that code as well — payloc91, Mar 28 '18 at 08:50

Unusual memory consumption in working with fragments

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