java - ConcurrentModificationException without modifying object -

-

i've got following piece of code causing concurrentmodificationexception. i'm not modifying products object @ all, 

list<product> products = product.findactivebyfilter(filters); set<long> temp = new hashset<long>(); list<product> resultsettemp = new arraylist<product>(); (product product : products) { // << exception points     if(!temp.contains(product.getid())){         temp.add(product.getid());         resultsettemp.add(product);     } } products.clear(); products.addall(resultsettemp);

i've seen exception pop-up several times, cannot reproduce (it happens randomly).

product.findactivebyfilter method returns new instance of list<product> has been build cached list<product>.

edit: i've found way reproduce error. code called when client wants products (its webshop), , website loads more items when client scrolls down. triggers exception (as server not-yet done responding products, , gets call it). race conditions, fun!

as said already, caused seperate tread 'modifying' products (as cached instance). i've changed implementation of product.findactivebyfilter return new arraylist<product>(products); instead of reference cached value, when no filters applied (thus no filtered result given back).

public static list<product> findactivebyfilter(arraylist<filterpair> filters) {     list<product> products = getcachedallproductsbyfirstsupplier();      if (products == null) {         products = new arraylist<product>();     }      if(filters.size() > 0) {         list<product> productsfiltered = new arraylist<product>(products);         // ... many checks here filters ...          return productsfiltered;     }      return new arraylist<product>(products); // not give cached copy, 'return products;' }

there 2 calls findactivebyfilter, called website. first 1 did include filter, second 1 did not (so first 1 still busy, while second 1 returned directly).


Comments

Post a Comment

Popular posts from this blog

java - WrongTypeOfReturnValue exception thrown when unit testing using mockito -

-
my test list<person> mylist; @test public void testisvalidperson() { mylist = new arraylist<person>(); mylist.add(new person("tom")); when(persondao.get(person)).thenreturn(mylist); when((persondao.get(person)).isempty()).thenreturn(false);//------exception thrown boolean result = service.isvalid("tom"); assertfalse(result); } method tested: public boolean isvalid(string person){ persondao = new persondao(); person personobj = new person(person); return (persondao.get(person).isempty())?false : true; } exception thrown: org.mockito.exceptions.misusing.wrongtypeofreturnvalue: boolean cannot returned get() get() should return list *** if you're unsure why you're getting above error read on. due nature of syntax above problem might occur because: 1. exception *might* occur in wrongly written multi-threaded tests. please refer mockito faq on limitations of concurrency testing. 2. sp
Read more

php - Magento - Deleted Base url key -

-
i working on cleaning url: http://mydomain.com/shop/shop/deals i going through settings in configuration tab in admin panel on magento , change secure , unsecure base urls remove first base url "shop" web page read: http://mydomain.com/shop/deals so changed unsecure base urls mydomain.com/shop mydomain.com , secure 12.345.67.89/shop 12.345.67.89. wrong thing do. i cannot reload page or admin console. how access these files through ftp , change correctly there?? when make changes in admin panel changes made in database not in file. have make changes in database. 1.go database , select core_config_data table under table find web/unsecure/base_url , web/secure/base_url . make changes here. don't forget clear cache in var/cache folder
Read more

android - How to disable Button if EditText is empty ? -

-
i have edittext , button in application. when button clicked,the text entered in edittext added listview. i want disable button if edittext empty.how ? this code button click imagebutton imb=(imagebutton)findviewbyid(r.id.btn_send); imb.setonclicklistener(new onclicklistener() { @override public void onclick(view arg0) { edittext et = (edittext)findviewbyid(r.id.edittext1); string str = et.gettext().tostring(); web1.add(str); toast.maketext(shoutsingleprogram.this, "you entered...."+str, toast.length_short).show(); adapter1.notifydatasetchanged(); et.settext(""); } }); } how can ? edittext1.addtextchangedlistener(new textwatcher() { @override public void ontextchanged(charsequence s, int start, int before, in
Read more