{"id":770,"date":"2018-11-28T05:23:52","date_gmt":"2018-11-28T02:23:52","guid":{"rendered":"http:\/\/delimuhendis.org\/?p=770"},"modified":"2022-12-20T21:10:26","modified_gmt":"2022-12-20T21:10:26","slug":"multithreading-3","status":"publish","type":"post","link":"https:\/\/www.delimuhendis.org\/?p=770","title":{"rendered":"Java ile Multithreading \u0130\u015flemleri-3 (Semaphore)"},"content":{"rendered":"\n

Merhaba arkada\u015flar, bug\u00fcn sizinle Java’da semaphore kullan\u0131m\u0131n\u0131 i\u015fleyece\u011fiz. Malumunuz t\u00fcm threadler e\u015f zamanl\u0131 olarak \u00e7al\u0131\u015f\u0131r ve java bunlardan ilk olu\u015fturulan\u0131n ilk \u00e7al\u0131\u015ft\u0131r\u0131laca\u011f\u0131n\u0131n garantisini vermez. \u00d6rnek verecek olursak biz Thread 1’in start() methodunu daha erken \u00e7a\u011f\u0131rmam\u0131za ra\u011fmen Thread 2 daha \u00f6nce \u00e7al\u0131\u015fmaya ba\u015flayabilir. Bu tarz durumlar bazen can s\u0131k\u0131c\u0131 olabilir. Bug\u00fcn sizinle ayn\u0131 i\u015flemi \u00f6nce normal olarak sonra da semaphore kullanarak yapaca\u011f\u0131z ve farklar\u0131 g\u00f6zlemleyece\u011fiz.<\/p>\n\n\n\n

ilk \u00f6nce a\u015fa\u011f\u0131daki kodu \u00e7al\u0131\u015ft\u0131ral\u0131m. G\u00f6rd\u00fc\u011f\u00fcn\u00fcz gibi \u00e7al\u0131\u015ft\u0131r\u0131ld\u0131\u011f\u0131 zaman yap\u0131c\u0131 method’da ge\u00e7ti\u011fimiz ideyi konsola yazan bir thread olu\u015fturduk ve bu \u015fekilde hangi thread’in daha \u00f6nce \u00e7al\u0131\u015fm\u0131\u015f oldu\u011funu anlad\u0131k.<\/p>\n\n\n\n

public class Main\n{\n    public static void main(String[] args)\n    {\n        for(int i = 0; i < 3; i++)\n        {\n            StandardThread thread = new StandardThread(i);\n            thread.start();\n        }\n    }\n}\n\nclass StandardThread extends Thread\n{\n    int id;\n    public StandardThread(int id)\n    {\n        this.id = id;\n    }\n    public void run()\n    {\n        System.out.println(id);\n    }\n}<\/pre>\n\n\n\n
Sonu\u00e7<\/p>\n\n\n\n
0\n2\n1<\/code><\/pre>\n\n\n\n
G\u00f6rd\u00fc\u011f\u00fcn\u00fcz gibi 1 numaral\u0131 thread’in start() methodu 2 numaral\u0131 threadinkinden \u00f6nce \u00e7a\u011fr\u0131lmas\u0131na ra\u011fmen Thread 2 daha erken \u00e7al\u0131\u015ft\u0131. Bu durum s\u0131ralaman\u0131n \u00f6nde oldu\u011fu programlarda soruna neden olabilir. \u015eimdi bu sorunu Semaphore kullanarak \u00e7\u00f6zece\u011fiz.<\/p>\n\n\n\n
import java.util.concurrent.Semaphore;\n\npublic class Main\n{\n    public static void main(String[] args)\n    {\n        Semaphore semaphore = new Semaphore(1);\n\n        for(int i = 0; i < 3; i++)\n        {\n            new SemaphoreThread(semaphore,i).start();\n        }\n    }\n}\n\n<\/pre>\n\n\n\n
class SemaphoreThread extends Thread\n{\n    Semaphore semaphore;\n    int id;\n    public SemaphoreThread(Semaphore semaphore,int id)\n    {\n        this.semaphore = semaphore;\n        this.id = id;\n    }\n\n    public void run()\n    {\n        try\n        {\n            semaphore.acquire();\n            System.out.println(id);\n        }\n        catch (Exception ex)\n        {\n\n        }\n        finally {\n            semaphore.release();\n        }\n    }\n}<\/pre>\n\n\n\n
Sonu\u00e7<\/p>\n\n\n\n
0\n1\n2<\/code><\/pre>\n\n\n\n
G\u00f6rd\u00fc\u011f\u00fcn\u00fcz gibi sonu\u00e7lar\u0131 gayet d\u00fczg\u00fcn bir s\u0131rayla ald\u0131k. \u015eimdi size s\u0131rayla ad\u0131mlar\u0131 anlataca\u011f\u0131m. \u0130lk ad\u0131mda Main thread i\u00e7erisinde Semaphore tipinden bir nesne olu\u015fturduk. Bu nesneye 1 parametresini verdik. Bu bir semaphore’u serbest b\u0131rakmadan yani release() methodunu \u00e7a\u011f\u0131rmadan maksimum ka\u00e7 threadin \u00e7al\u0131\u015ft\u0131r\u0131labilece\u011finin iznidir. \u00d6rne\u011fin ona 2 yazarsak release etmeden 3.thread \u00e7al\u0131\u015fmaz. Biz ona bir de\u011feri verdik. Thread \u00e7al\u0131\u015f\u0131r \u00e7al\u0131\u015fmaz acquire() methodunu \u00e7a\u011f\u0131rarak semaphore’u ba\u015flatt\u0131k ve \u00e7al\u0131\u015fmas\u0131n\u0131 istedi\u011fimiz kodu yazd\u0131k. i\u015flem sonunda da release() methodunu \u00e7a\u011f\u0131rarak semaphore’u serbest b\u0131rakt\u0131k.<\/p>\n","protected":false},"excerpt":{"rendered":"
Merhaba arkada\u015flar, bug\u00fcn sizinle Java’da semaphore kullan\u0131m\u0131n\u0131 i\u015fleyece\u011fiz. Malumunuz t\u00fcm threadler e\u015f zamanl\u0131 olarak \u00e7al\u0131\u015f\u0131r ve java bunlardan ilk olu\u015fturulan\u0131n…<\/p>\n","protected":false},"author":1,"featured_media":1390,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[18,302,395,471,502,558],"class_list":["post-770","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-programlama","tag-acquire","tag-java","tag-multithreading","tag-release","tag-semaphore","tag-thread"],"_links":{"self":[{"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=\/wp\/v2\/posts\/770","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=770"}],"version-history":[{"count":2,"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=\/wp\/v2\/posts\/770\/revisions"}],"predecessor-version":[{"id":1391,"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=\/wp\/v2\/posts\/770\/revisions\/1391"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=\/wp\/v2\/media\/1390"}],"wp:attachment":[{"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=770"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=770"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.delimuhendis.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=770"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}