memleak in fphttpclient?

[billyb123]

valgrind says this prog leaks memory (about 80kb).
BUT i noticed when i put 'http' (for example, http://www.example.com/) instead of 'https' it doesnt leak memory.

can someone explain this to me? why do i have memleak here?

Code: [Select]

{$MODE DELPHI}
program test;
uses
  fphttpclient;

const
  url = 'https://api.darksky.net/';

var
  page: ansistring;
  http: tfphttpclient;

begin
  http := tfphttpclient.create (nil);
  try
    page := http.get (url);
  finally
    http.free;
  end;
  writeln (page);
end.


[Thaddy]

fphttpclient uses sslsockets for https.(in the implementation uses clause)
80Kb looks like a context not being free'd by sslsockets.
I would not worry too much unless the leak is progressive (increases when doing multiple https visits).
Will have a look.

[molly]

Would be great if you could have a look Thaddy. Secure or not, heaptrc keeps telling me there is leakage (3.0, win32)

[rvk]

I'm getting an 404 exception with your program (with that page).

Try the following:

Code: Pascal  [Select][+][-]

1. {$MODE DELPHI}
2. program project1;
3. uses
4.   fphttpclient;
5.  
6. const
7.   url = 'https://api.darksky.net/';
8.  
9. var
10.   page: ansistring;
11.   http: tfphttpclient;
12.  
13. begin
14.   http := tfphttpclient.create (nil);
15.   try
16.     try
17.       page := http.get (url);
18.     except
19.       writeln('woops, exception');
20.     end;
21.   finally
22.     http.free;
23.   end;
24.   writeln (page);
25. end.

So without proper exception handling it seems not everything is freed. With above example I don't get a leak.

[molly]

Thanks rvk, i can confirm.

Strange.

[rvk]

Yes. Without the exception handling this is what I get.
So the page returns a 404.
Get only expects a 200 and otherwise throws an exception.

Internally there is a leak that with throwing an exception something is not freed.
But then it's weird that if I handle the exception at a higher level that block does get freed.

Code: [Select]

An unhandled exception occurred at $00414579:
EHTTPClient: Unexpected response status code: 404
  $00414579  TFPCUSTOMHTTPCLIENT__READRESPONSE,  line 1089 of ./fcl-web/src/base/fphttpclient.pp
  $00414E75  TFPCUSTOMHTTPCLIENT__DONORMALREQUEST,  line 1179 of ./fcl-web/src/base/fphttpclient.pp
  $00415133  TFPCUSTOMHTTPCLIENT__DOMETHOD,  line 1232 of ./fcl-web/src/base/fphttpclient.pp
  $004156A9  TFPCUSTOMHTTPCLIENT__HTTPMETHOD,  line 1331 of ./fcl-web/src/base/fphttpclient.pp
  $00415867  TFPCUSTOMHTTPCLIENT__GET,  line 1367 of ./fcl-web/src/base/fphttpclient.pp
  $004158BC  TFPCUSTOMHTTPCLIENT__GET,  line 1398 of ./fcl-web/src/base/fphttpclient.pp
  $0040180A  main,  line 16 of project1.lpr

Heap dump by heaptrc unit
376 memory blocks allocated : 17237/18384
372 memory blocks freed     : 17080/18216
4 unfreed memory blocks : 157
True heap size : 491520 (96 used in System startup)
True free heap : 490960
Should be : 491000
Call trace for block $01814660 size 64
  $00409D6C  fpc_raiseexception,  line 165 of C:/dev/fpc/rtl/inc/except.inc
  $004145B3  TFPCUSTOMHTTPCLIENT__READRESPONSE,  line 1090 of ./fcl-web/src/base/fphttpclient.pp
  $00414E75  TFPCUSTOMHTTPCLIENT__DONORMALREQUEST,  line 1179 of ./fcl-web/src/base/fphttpclient.pp
  $00415133  TFPCUSTOMHTTPCLIENT__DOMETHOD,  line 1232 of ./fcl-web/src/base/fphttpclient.pp
  $004156A9  TFPCUSTOMHTTPCLIENT__HTTPMETHOD,  line 1331 of ./fcl-web/src/base/fphttpclient.pp
  $00415867  TFPCUSTOMHTTPCLIENT__GET,  line 1367 of ./fcl-web/src/base/fphttpclient.pp
  $004158BC  TFPCUSTOMHTTPCLIENT__GET,  line 1398 of ./fcl-web/src/base/fphttpclient.pp
  $0040180A  main,  line 16 of project1.lpr
Call trace for block $0174D9D8 size 24
  $00409D6C  fpc_raiseexception,  line 165 of C:/dev/fpc/rtl/inc/except.inc
  $004145B3  TFPCUSTOMHTTPCLIENT__READRESPONSE,  line 1090 of ./fcl-web/src/base/fphttpclient.pp
  $00414E75  TFPCUSTOMHTTPCLIENT__DONORMALREQUEST,  line 1179 of ./fcl-web/src/base/fphttpclient.pp
  $00415133  TFPCUSTOMHTTPCLIENT__DOMETHOD,  line 1232 of ./fcl-web/src/base/fphttpclient.pp
  $004156A9  TFPCUSTOMHTTPCLIENT__HTTPMETHOD,  line 1331 of ./fcl-web/src/base/fphttpclient.pp
  $00415867  TFPCUSTOMHTTPCLIENT__GET,  line 1367 of ./fcl-web/src/base/fphttpclient.pp
  $004158BC  TFPCUSTOMHTTPCLIENT__GET,  line 1398 of ./fcl-web/src/base/fphttpclient.pp
  $0040180A  main,  line 16 of project1.lpr
Call trace for block $0178CA60 size 49
  $0042434B  FORMAT,  line 403 of C:/dev/fpc/rtl/objpas/sysutils/sysformt.inc
  $00424822  FORMAT,  line 1066 of C:/dev/fpc/rtl/objpas/sysutils/sysstr.inc
  $00427D9E  EXCEPTION__CREATEFMT,  line 190 of C:/dev/fpc/rtl/objpas/sysutils/sysutils.inc
  $004145A7  TFPCUSTOMHTTPCLIENT__READRESPONSE,  line 1090 of ./fcl-web/src/base/fphttpclient.pp
  $00414E75  TFPCUSTOMHTTPCLIENT__DONORMALREQUEST,  line 1179 of ./fcl-web/src/base/fphttpclient.pp
  $00415133  TFPCUSTOMHTTPCLIENT__DOMETHOD,  line 1232 of ./fcl-web/src/base/fphttpclient.pp
  $004156A9  TFPCUSTOMHTTPCLIENT__HTTPMETHOD,  line 1331 of ./fcl-web/src/base/fphttpclient.pp
  $00415867  TFPCUSTOMHTTPCLIENT__GET,  line 1367 of ./fcl-web/src/base/fphttpclient.pp
Call trace for block $0174D978 size 20
  $004145A7  TFPCUSTOMHTTPCLIENT__READRESPONSE,  line 1090 of ./fcl-web/src/base/fphttpclient.pp
  $00414E75  TFPCUSTOMHTTPCLIENT__DONORMALREQUEST,  line 1179 of ./fcl-web/src/base/fphttpclient.pp
  $00415133  TFPCUSTOMHTTPCLIENT__DOMETHOD,  line 1232 of ./fcl-web/src/base/fphttpclient.pp
  $004156A9  TFPCUSTOMHTTPCLIENT__HTTPMETHOD,  line 1331 of ./fcl-web/src/base/fphttpclient.pp
  $00415867  TFPCUSTOMHTTPCLIENT__GET,  line 1367 of ./fcl-web/src/base/fphttpclient.pp
  $004158BC  TFPCUSTOMHTTPCLIENT__GET,  line 1398 of ./fcl-web/src/base/fphttpclient.pp
  $0040180A  main,  line 16 of project1.lpr
  $004158BC  TFPCUSTOMHTTPCLIENT__GET,  line 1398 of ./fcl-web/src/base/fphttpclient.pp

[molly]

in case it matter, i tried simple www.google.com and that throws a 302 with similar outcome (mode objfpc).

[rvk]

The problem isn't in fphttpclient at all. It is in sysutils.

When you don't handle an exception in your console program and sysutils is used... you get a leak when the program ends. This is only when the finalization handles the exception.

Example:

Code: Pascal  [Select][+][-]

1. program project1;
2. uses sysutils;
3. var
4.   i: integer;
5. begin
6.   try
7.     i := 0;
8.     i := 7 div i;
9.   finally
10.     writeln('finally');
11.   end;
12.   writeln('normal end');
13. end.

Solution... always handle any exception in a console program when you're using sysutils (which is used by fphttpclient). It's also not a recurring leak (only when the program end, so it might not matter a lot).

[billyb123]

your example still leaks here.
if i put a normal address in url like 'https://webflow.com/discover/popular' which gets http response 200, and the 'except' section, it still leaks 80kb.

I'm getting an 404 exception with your program (with that page).

Try the following:

Code: Pascal  [Select][+][-]

1. {$MODE DELPHI}
2. program project1;
3. uses
4.   fphttpclient;
5.  
6. const
7.   url = 'https://api.darksky.net/';
8.  
9. var
10.   page: ansistring;
11.   http: tfphttpclient;
12.  
13. begin
14.   http := tfphttpclient.create (nil);
15.   try
16.     try
17.       page := http.get (url);
18.     except
19.       writeln('woops, exception');
20.     end;
21.   finally
22.     http.free;
23.   end;
24.   writeln (page);
25. end.

So without proper exception handling it seems not everything is freed. With above example I don't get a leak.

[rvk]

your example still leaks here.
if i put a normal address in url like 'https://webflow.com/discover/popular' which gets http response 200, and the 'except' section, it still leaks 80kb.

Not for me. Source below gives me:

Code: [Select]

no leak. page-length: 402866
Heap dump by heaptrc unit
379 memory blocks allocated : 20288435/20289736
379 memory blocks freed     : 20288435/20289736
0 unfreed memory blocks : 0
True heap size : 425984 (160 used in System startup)
True free heap : 425824On:
Lazarus 1.2.0 / FPC 2.6.2 32 bit
Lazarus 1.6.2 / FPC 3.0.0 64 bit
Lazarus 1.7 trunk / FPC 3.1.1 32 bit

Code: Pascal  [Select][+][-]

1. {$MODE DELPHI}
2. program project1;
3. uses
4.   fphttpclient;
5.  
6. const
7.   url = 'https://webflow.com/discover/popular';
8.  
9. var
10.   page: ansistring;
11.   http: tfphttpclient;
12.  
13. begin
14.   http := tfphttpclient.create (nil);
15.   try
16.     try
17.       page := http.get (url);
18.     except
19.       writeln('woops, exception');
20.     end;
21.   finally
22.     http.free;
23.   end;
24.   // writeln (page);
25.   writeln ('no leak. page-length: ', length(page));
26. end.

[Thaddy]

@rvk
Same here. No leaks after program termination.

Code: [Select]

no leak. page-length: 402866
Heap dump by heaptrc unit
468 memory blocks allocated : 20291888/20293664
468 memory blocks freed     : 20291888/20293664
0 unfreed memory blocks : 0
True heap size : 425984
True free heap : 425984