c# - Why an unreferenced object is not collected? -

-

this program prints "true" console.

allocate object, make weakreference of that, go out of block scope, , check weakreference.isalive.

public static void main (string[] args) {     test (); }  static void test () {     weakreference wref = null;      { // block scope         var obj = new object ();         wref = new weakreference (obj);     }      // obj out of scope     // console.writeline (obj);      gc.collect ();      console.writeline (wref.isalive); // => true }

why obj not collected, though obj out of scope?

the program compiled mono 3.12.0.

edit:

sorry, inappropriate example.

the following program print true. block scope seems not related. tried not debug mode.

    public static void main (string[] args)     {         test ();     }      static void test ()     {         weakreference wref = null;          var obj = new object ();         wref = new weakreference (obj);         obj = null;          gc.collect ();          console.writeline (wref.isalive); // => true     } 
$ mcs -debug- program.cs $ mono program.exe

you expect gc 100% deterministic, when it's not.

a few things might have happened:

  • the jit optimized null assignment away.
  • a pointer instance can left on in temporary stack location, or in register (you called function, passing variable, put variable in register on architectures).

Comments

Post a Comment

Popular posts from this blog

rewrite asp to php based on asp query -

-
i have seen several questions similar , tried solutions @ loss. need redirect example.com/products.asp?lob=health to example.com/services/healthcare/ i need several lob= different value . there way can redirect each url. maybe kind of rewrite condition on lob if value of lob = health, redirect here. if equals home, redirect somewhere else? not sure "correct" way works. rewritecond %{query_string} ^lob=value1$ [nc] rewriterule ^products.asp$ http://example.org/sample/one/? [r=301,l] and different value: rewritecond %{query_string} ^lob=value2$ [nc] rewriterule ^products.asp$ http://example.org/sample/two/? [r=301,l] and doesn't match value: rewriterule ^products\.asp$ [insert new url here] [r=301,l] the last example works if want redirect .asp url .php. keep in mind have other conditions , rules removing .php extension , adding / files: rewritecond %{request_filename} !-f rewriterule ^([^/]+)/$ $1.php rewriterule ^([^/]+)/([^/]+)/$ /$1...
Read more

android - questions about switching from C2DM to GCM -

-
i'm converting app c2dm gcm , have questions. i've modified gcmquickstart example found here: git clone https://github.com/googlesamples/google-services.git in class extends application, i've got: public class myapp extends application { @override public void oncreate() { super.oncreate(); if (this.checkplayservices()) { intent intent = new intent(this, registrationintentservice.class); startservice(intent); } else{ log.e(tag,"failed checkforgcm"); } } } afaik, starts service , it'll run forever or if operating system shuts down whereupon operating system restart it. correct? checkplayservices() makes sure android 2.3 or greater , google play services installed these requirements use gcm. correct? public class registrationintentservice extends intentservice{ private static final string tag = "regintentservice"; public registratio...
Read more

visual studio 2010 - Error on RDLC Expression -

-
i using exp calculate total fees paid on rdlc report: =sum(iif(fields!responsedescription.value ="approved successful",int(fields!amount.value), 0)) and #error in resulting column , can issue ? . and similar exp above work fine : =sum(iif(fields!responsedescription.value <> "",int(fields!amount.value), 0)) few notes: 1- amount integer , present. 2- responsedescription string , present. thank you you can use expression: =sum(cint(iif(fields!responsedescription.value ="approved successful", fields!amount.value, 0))) you have convert every possible values same type before aggregation. i think second expression works fine because in true case ( fields!responsedescription.value <> "" ) used expression converted integer .
Read more