Question

我为Tomcat8服务器创建了一个WebApp。这是一款基于网络的小游戏。

由于我已从flatfiles切换到MySQL，因此javax.json builder存在很多问题。

这是我的代码部分：

public void saveUserResearch(){
    MySQLTable t = SpaceWar.instance().getUserResearchTable();

    JsonObjectBuilder mainBuilder = Json.createObjectBuilder();
    JsonObjectBuilder subBuilder = Json.createObjectBuilder();
    for(UserResearch r : getResearchList()){
        int index = r.getIndex();
        subBuilder = Json.createObjectBuilder();
        subBuilder.add("index", r.getIndex());
        subBuilder.add("level", r.getLevel());
        subBuilder.add("planed_level", r.getPlanedLevel());
        subBuilder.add("player_uuid", r.getPlayerUUIDAsString());
        subBuilder.add("unlocked", r.getUnlocked());
        subBuilder.add("savedInPlayer", "yes");
        mainBuilder.add(index+"", subBuilder.build());
    }
    String q = "";
    q += "user_uuid:" + getUUID().toString() + ";";
    q += "research_json:" + mainBuilder.build();
    t.insertUpdate(q).sync();

}

Maven依赖：

<!-- https://mvnrepository.com/artifact/javax.json/javax.json-api -->
        <dependency>
            <groupId>javax.json</groupId>
            <artifactId>javax.json-api</artifactId>
            <version>1.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.glassfish/javax.json -->
        <dependency>
            <groupId>org.glassfish</groupId>
            <artifactId>javax.json</artifactId>
            <version>1.0.4</version>
        </dependency>

我每隔2分钟从一个线程调用此方法。我在游戏中有15个用户，所以它运行了15次。它创建了一个JSON对象和我保存到MySQL DB的JSON对象。所以我期待15个实例。

问题是几个小时后，Tomcat服务器崩溃并显示以下消息。

Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x00000007b5400000, 1048576, 0) failed; error='Cannot allocate memory' (errno=12)

 There is insufficient memory for the Java Runtime Environment to continue.
 Native memory allocation (mmap) failed to map 1048576 bytes for committing reserved memory.
 An error report file with more information is saved as:
 /tmp/hs_err_pid11069.log

所以我决定使用VisualVM来查看它，在那里我发现了很多麻烦。