when add the third node program exit

[kevin-gjm]

hi
when I add the third node program exit.
ERROR msg: EINVAL: invalid argument

raft server me->entries[0] will change in the log_offer handler: __raft_logentry_offer

    e = mdb_txn_begin(sv->db_env, NULL, 0, &txn);
    if (0 != e)
        mdb_fatal(e);
    e = mdb_get(txn, sv->entries, &key, &val);
    switch (e)
    {
    case 0:
        break;
    default:
        mdb_fatal(e);
    }
    ety->data.buf = val.mv_data;
    ety->data.len = val.mv_size;

[kevin-gjm]

OK,I konw why do this!
but

struct MDB_val
Generic structure used for passing keys and data in and out of the database. 
Values returned from the database are valid only until a subsequent update operation, 
**or the end of the transaction**. Do not modify or free them, they commonly point into the database itself.

Here, after use the transaction.the value still valid ?? !!
Before I append entry 3 ,the first entry buf is 0x5c78efb0. After append entry 3 it changes to 0x5c78bfb0

[q96456]

how to solve the problem that program exit when I add the third node？