FileDB records access time drastically changes on application restart

[pawan singh]

Dear Team,

I am using file db in multi threaded application where user requests are being served from file cache.

-- On application start if new file cache is getting created then response time is very high starting from 10ms to 1000ms and even more.

-- On application start if existing file is being opened then response time is very low like 0 to 2 ms.

-- Now if we reload existing file cache then again response time is getting increased

I am not sure why is it happening, below mentioned is piece of code that i am using in my application.

DB db = DBMaker.fileDB(file) // file db
        .fileMmapEnable() // enable memory map file
        .fileMmapPreclearDisable().cleanerHackEnable().closeOnJvmShutdown().transactionEnable()
        .allocateStartSize(2 * 1024 * 1024 * 1024) // 2GB
        .allocateIncrement(64 * 1024 * 1024) // 64MB
        .make();

HTreeMap<String, String> hTreeMap = db.hashMap("mydb",Serializer.STRING, Serializer.STRING)
        .layout(64 // concurrency
            , 16 // node size
            , 4 // levels in index tree
        ).counterEnable().createOrOpen();

To get elements hTreeMap.get(key);

and to put hTreeMap.put(key, value);

db.commit();