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firemonkeyc++builder

TScrollBox or TChart memory leak (FMX, C++)

I've been trying to find a memory leak on iOS and i'm 99% it is either in a TScrollBox or in a TChart. The action that leads to the crash is simple scrolling back and forth across the TChart. The app behaves well in Win32 and memory useage is stable.

The crash cause on iOS is EXC_RESOURCE -> myappname[5548] exceeded mem limit: ActiveHard 1400MB (fatal) per Xcode Console.

To exclude my spaghetti code as the culprit i created a simple project to reproduce the error and it crashes too. Below are snips from the Xcode Console output. I get tons of assertions, then the Received memory warning, then the iOS kernal kills my app (Project1).

default 20:28:26.180333 -0500 assertiond [Project1:7693] Activate assertion: <BKProcessAssertion: 0x12b0102c0; "com.apple.UIKit.KeyboardManagement.message" (finishTask:180s); id:…8EA7F5E94DD5> default 20:28:26.180542 -0500 assertiond [Project1:7693] Setting jetsam priority to 10 [0x10108] default 20:28:26.182151 -0500 assertiond [Project1:7693] Deactivate assertion: <BKProcessAssertion: 0x12b0102c0; "com.apple.UIKit.KeyboardManagement.message" (finishTask:180s); id:…8EA7F5E94DD5> default 20:28:26.182312 -0500 assertiond [Project1:7693] Setting jetsam priority to 10 [0x10100] default 20:28:26.183307 -0500 assertiond [Project1:7693] Remove assertion: <BKProcessAssertion: 0x12b0102c0; "com.apple.UIKit.KeyboardManagement.message" (finishTask:180s); id:…8EA7F5E94DD5> default 20:28:32.609723 -0500 Project1 Received memory warning.

Then a short time later i see the following console message:

default 20:28:45.881914 -0500 kernel EXC_RESOURCE -> Project1[7693] exceeded mem limit: ActiveHard 1400 MB (fatal).

My crash test app is a simple Firemonkey app built in C++ Builder 10.3.2.

A) Put a TPanel on the form (Panel1).

B) Put a TScrollBox on Panel1 (ScrollBox1). Set its align to Contents.

C) Put a TLayout on ScrollBox1 (Layout1). Set its align to None. Set its width to 2100.

D) Put a TChart on Layout1. Set its height to 200, width 7300. Set its align to None.

E) Add a TToolBar to Form1 and put a TButton on it.

F) Then put this code in the TButton's click event:

Form1->Layout1->Position->X = 0;
Form1->ChartTest->Position->Y = 0;
Form1->ChartTest->Position->X = 0;

TLineSeries *series1 = new TLineSeries(Form1);
TLineSeries *series2 = new TLineSeries(Form1);
TLineSeries *series3 = new TLineSeries(Form1);
TLineSeries *series4 = new TLineSeries(Form1);

series1->Color = claBlue; 
series2->Color = claRed;
series3->Color = claBlueviolet;
series4->Color = claAqua;

double x, y;
for (int i = 0; i < 1000; i++) {
 x = i;
 y = Random(5000);
 series1->AddXY(x,y);
 y = Random(5000);
 series2->AddXY(x,y);
 y = Random(5000);
 series3->AddXY(x,y);
 y = Random(5000);
 series4->AddXY(x,y);
}

Form1->ChartTest->AddSeries(series1);
Form1->ChartTest->AddSeries(series2);
Form1->ChartTest->AddSeries(series3);
Form1->ChartTest->AddSeries(series4);

G) And now, with your iOS device connected to your mac and Xcode Console open, filter the Console output on "Project1" if that is what you named it. Then run the app and scroll backwards/forwards and/or up/down (also change orientation if you want back and forth). You will see tons of assertions. Eventually (takes around 2-3 minutes of this harassment to make it crash) it will eat up enough memory that it crashes.

I think the memory leak is in the TeeChart most likely, maybe in the TScrollBox?

thanks, russ

Solution

  • The memory leak is in the TChart. I created another simple project with no scrollbox and i added a timer that moves the TChart up and down every 0.1 seconds. After 2-3 minutes it crashes on memory error on iOS with no user input after clicking Button1 to start things off. This crash occurs with no scrolling or any interaction - just the chart wiggling around.

    Testing the app on Win32 works fine - memory is stable and not growing.

    So, i'm hoping there is something obvious in how i create the chart that is the deficiency - i really don't want to abandon ship as Steema charts are so flexible. I've also posted to the Steema forum's but due to low volume there i'm posting here too.

    Any ideas? Note i'm also using a licensed version of TeeChart Standard VCL/FMX released May 30, 2019 - Build 2019.27.190530. I also ran a test case where the chart is stationary (no user input and no timer event moving the chart around) and no crash. It has to do with the chart being rejiggered somehow. I tried Form1->ChartTest->AutoRepaint = false; but had no effect. The zipped test project is here: Project1a

    thanks, russ

    UPDATE: The memory leak bug is present in TeeChart Standard build 2019.27.190530 but is not present in the free/lite version that comes stock with Rad Studio 10.3.2 as of now (version v2016.17.160129).