HIgh DIsk I/O due to Broker

Hi all,
I observed very high disk I/O on the broker.This usually happens when we are loading lookups.
But it is was longer than usual this time.
Our lookup storage is offheap.And the lookup file(druidMapDB) maintained by broker is around 10GB.
Through iotop, I found out that one of the broker threads was doing heavy writes(94GB in one hour).
I’m not sure what it was trying to write.I am assuming that it was modifying the lookup file.
The size of the file was constant after some time but there were still heavy writes.
Doing a strace on the thread I got ,
futex(0x7fe8ffe30ef8, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fe8ffe30f24, FUTEX_WAIT_BITSET_PRIVATE, 1, {24615113, 979949896}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
futex(0x7fe8ffe30ef8, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fe8ffe30f24, FUTEX_WAIT_BITSET_PRIVATE, 1, {24615114, 80170533}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
futex(0x7fe8ffe30ef8, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fe8ffe30f24, FUTEX_WAIT_BITSET_PRIVATE, 1, {24615114, 180373780}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
futex(0x7fe8ffe30ef8, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fe8ffe30f24, FUTEX_WAIT_BITSET_PRIVATE, 1, {24615114, 280538608}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
futex(0x7fe8ffe30ef8, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fe8ffe30f24, FUTEX_WAIT_BITSET_PRIVATE, 1, {24615114, 380743875}, ffffffff) = -1 ETIMEDOUT (Connection timed out)
futex(0x7fe8ffe30ef8, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fe8ffe30f24, FUTEX_WAIT_BITSET_PRIVATE, 1, {24615114, 480952702}, ffffffff) = -1 ETIMEDOUT (Connection timed out)

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My druid version is 0.12.3.I am able to query the broker.
what else can I explore to debug the "timed out " message ?

Can you trace the process id that correlates to this issue?

Rommel Garcia