mapdb wal file commit after program crash with no close

I wonder whether there are some way to write back those wal files ?

I config a mapdb with no shutdown hook, my program crashed, there are so many wal file in my mapPath. when I reopen my the mapdb, I find I lose part of my data, and then try commit, the wal files are still keeped;

            mydb = DBMaker
                    .fileDB(mapPath)
                    .fileMmapEnable()
                    .fileMmapEnableIfSupported()
                    .fileMmapPreclearDisable()
                    .cleanerHackEnable()
                    .checksumHeaderBypass()
                    .transactionEnable()
                    .make();