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POCan a Java HashMap's size() be out of sync with its actual entries' size?
 

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  1. POCan a Java HashMap's size() be out of sync with its actual entries' size?
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    <p>I have a Java HashMap called statusCountMap.<br> Calling size() results in 30.<br> But if I count the entries manually, it's 31<br> This is in one of my TestNG unit tests. These results below are from Eclipse's Display window (type code -> highlight -> hit Display Result of Evaluating Selected Text). </p> <pre> statusCountMap.size() (int) 30 statusCountMap.keySet().size() (int) 30 statusCountMap.values().size() (int) 30 statusCountMap (java.util.HashMap) {40534-INACTIVE=2, 40526-INACTIVE=1, 40528-INACTIVE=1, 40492-INACTIVE=3, 40492-TOTAL=4, 40513-TOTAL=6, 40532-DRAFT=4, 40524-TOTAL=7, 40526-DRAFT=2, 40528-ACTIVE=1, 40524-DRAFT=2, 40515-ACTIVE=1, 40513-DRAFT=4, 40534-DRAFT=1, 40514-TOTAL=3, 40529-DRAFT=4, 40515-TOTAL=3, 40492-ACTIVE=1, 40528-TOTAL=4, 40514-DRAFT=2, 40526-TOTAL=3, 40524-INACTIVE=2, 40515-DRAFT=2, 40514-ACTIVE=1, 40534-TOTAL=3, 40513-ACTIVE=2, 40528-DRAFT=2, 40532-TOTAL=4, 40524-ACTIVE=3, 40529-ACTIVE=1, 40529-TOTAL=5} statusCountMap.entrySet().size() (int) 30 </pre> <p>What gives ? Anyone has experienced this ?<br> I'm pretty sure statusCountMap is not being modified at this point.<br> There are 2 methods (lets call them methodA and methodB) that modify statusCountMap <strong>concurrently</strong>, by repeatedly calling incrementCountInMap.</p> <pre> private void incrementCountInMap(Map map, Long id, String qualifier) { String key = id + "-" + qualifier; if (map.get(key) == null) { map.put(key, 0); } synchronized (map) { map.put(key, map.get(key).intValue() + 1); } } </pre> <p>methodD is where I'm getting the issue. methodD has a TestNG @dependsOnMethods = { "methodA", "methodB" } so when methodD is executing, statusCountMap is pretty much static already. I'm mentioning this because it might be a bug in TestNG.<br> I'm using Sun JDK 1.6.0_24. TestNG is testng-5.9-jdk15.jar </p> <p>Hmmm ... after rereading my post, could it be because of concurrent execution of outside-of-synchronized-block map.get(key) == null &amp; map.put(key,0) that's causing this issue ?</p>
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      1. POCan a Java HashMap's size() be out of sync with its actual entries' size?
      1. USDeepak
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      1. POCan a Java HashMap's size() be out of sync with its actual entries' size?
      1. USStan Kurilin
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      1. POCan a Java HashMap's size() be out of sync with its actual entries' size?
      1. USAdam Paynter
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    1. COcan you show all the code? maybe one is a default entry, try 20 entries see if you get 21
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      1. POCan a Java HashMap's size() be out of sync with its actual entries' size?
      1. USVladp
    2. COHow do you count?
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      1. POCan a Java HashMap's size() be out of sync with its actual entries' size?
      1. USErik
    3. COI just count how many entries there are in {40534-INACTIVE=2, 40526-INACTIVE=1, 40528-INACTIVE=1, 40492-INACTIVE=3, 40492-TOTAL=4, 40513-TOTAL=6, 40532-DRAFT=4, 40524-TOTAL=7, 40526-DRAFT=2, 40528-ACTIVE=1, 40524-DRAFT=2, 40515-ACTIVE=1, 40513-DRAFT=4, 40534-DRAFT=1, 40514-TOTAL=3, 40529-DRAFT=4, 40515-TOTAL=3, 40492-ACTIVE=1, 40528-TOTAL=4, 40514-DRAFT=2, 40526-TOTAL=3, 40524-INACTIVE=2, 40515-DRAFT=2, 40514-ACTIVE=1, 40534-TOTAL=3, 40513-ACTIVE=2, 40528-DRAFT=2, 40532-TOTAL=4, 40524-ACTIVE=3, 40529-ACTIVE=1, 40529-TOTAL=5}
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