explore node oom

fatal error: runtime: out of memory

runtime stack:
runtime.throw(0x160d367, 0x16)
        /usr/local/go/src/runtime/panic.go:1114 +0x72
runtime.sysMap(0xc0dc000000, 0x8000000, 0x287c3b8)
        /usr/local/go/src/runtime/mem_linux.go:169 +0xc5
runtime.(*mheap).sysAlloc(0x285c160, 0x7400000, 0x285c168, 0x386b)
        /usr/local/go/src/runtime/malloc.go:715 +0x1cd
runtime.(*mheap).grow(0x285c160, 0x386b, 0x0)
        /usr/local/go/src/runtime/mheap.go:1286 +0x11c
runtime.(*mheap).allocSpan(0x285c160, 0x386b, 0x100, 0x287c3c8, 0xfffffffffffffade)
        /usr/local/go/src/runtime/mheap.go:1124 +0x6a0
runtime.(*mheap).alloc.func1()
        /usr/local/go/src/runtime/mheap.go:871 +0x64
runtime.(*mheap).alloc(0x285c160, 0x386b, 0x7faa2dde0001, 0x429270)
        /usr/local/go/src/runtime/mheap.go:865 +0x81
runtime.largeAlloc(0x70d6000, 0x460100, 0xc0d1eac000)
        /usr/local/go/src/runtime/malloc.go:1152 +0x92
runtime.mallocgc.func1()
        /usr/local/go/src/runtime/malloc.go:1047 +0x46
runtime.systemstack(0x7faa2dde9d30)
        /usr/local/go/src/runtime/asm_amd64.s:370 +0x66
runtime.mstart()
        /usr/local/go/src/runtime/proc.go:1041

goroutine 1343876 [running]:
runtime.systemstack_switch()
        /usr/local/go/src/runtime/asm_amd64.s:330 fp=0xc0127dd258 sp=0xc0127dd250 pc=0x466c20
runtime.mallocgc(0x70d6000, 0x0, 0x0, 0xc00abdcc40)
        /usr/local/go/src/runtime/malloc.go:1046 +0x895 fp=0xc0127dd2f8 sp=0xc0127dd258 pc=0x40e725
runtime.growslice(0x13c8fa0, 0x2879dc8, 0x0, 0x0, 0x70d52dc, 0x1af6140, 0xc000582e10, 0x1)
"harmony.err" [readonly] 136006L, 8951474C                                                                             1,1           Top
        /usr/local/go/src/runtime/malloc.go:1046 +0x895 fp=0xc0127dd2f8 sp=0xc0127dd258 pc=0x40e725
runtime.growslice(0x13c8fa0, 0x2879dc8, 0x0, 0x0, 0x70d52dc, 0x1af6140, 0xc000582e10, 0x1)
        /usr/local/go/src/runtime/slice.go:175 +0x14e fp=0xc0127dd360 sp=0xc0127dd2f8 pc=0x44e2be
github.com/syndtr/goleveldb/leveldb/table.(*Reader).find(0xc00cfc2680, 0xc00abdcc40, 0x35, 0x35, 0x1, 0x0, 0x7faa80149200, 0xc00abdccc0, 0x35, 0x40, ...)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/table/reader.go:904 +0x623 fp=0xc0127dd538 sp=0xc0127dd360 pc=0x9b3123
github.com/syndtr/goleveldb/leveldb/table.(*Reader).Find(...)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/table/reader.go:922
github.com/syndtr/goleveldb/leveldb.(*tOps).find(0xc0003eb230, 0xc00bedb2c0, 0xc00abdcc40, 0x35, 0x35, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/table.go:450 +0x13f fp=0xc0127dd5d8 sp=0xc0127dd538 pc=0x9df4ff
github.com/syndtr/goleveldb/leveldb.(*version).get.func1(0x0, 0xc00bedb2c0, 0xc00abdcc40)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/version.go:180 +0x458 fp=0xc0127dd6e8 sp=0xc0127dd5d8 pc=0x9e9618
github.com/syndtr/goleveldb/leveldb.(*version).walkOverlapping(0xc00cbe27e0, 0x0, 0x0, 0x0, 0xc00abdcc40, 0x35, 0x35, 0xc0127dd858, 0xc0127dd828)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/version.go:119 +0x2a8 fp=0xc0127dd7a8 sp=0xc0127dd6e8 pc=0x9e13b8
github.com/syndtr/goleveldb/leveldb.(*version).get(0xc00cbe27e0, 0x0, 0x0, 0x0, 0xc00abdcc40, 0x35, 0x35, 0x0, 0xa49f00, 0x0, ...)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/version.go:164 +0x2dd fp=0xc0127dd900 sp=0xc0127dd7a8 pc=0x9e190d
github.com/syndtr/goleveldb/leveldb.(*DB).get(0xc0001b2380, 0x0, 0x0, 0x0, 0x0, 0xc019e01650, 0x2d, 0x30, 0x161d, 0x0, ...)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/db.go:785 +0x381 fp=0xc0127dda18 sp=0xc0127dd900 pc=0x9bece1
github.com/syndtr/goleveldb/leveldb.(*DB).Get(0xc0001b2380, 0xc019e01650, 0x2d, 0x30, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
        /home/ec2-user/go/pkg/mod/github.com/syndtr/[email protected]/leveldb/db.go:851 +0x13b fp=0xc0127ddac0 sp=0xc0127dda18 pc=0x9bf4cb
github.com/harmony-one/harmony/api/service/explorer.(*Storage).UpdateTxAddressStorage(0xc0003f0040, 0xc00a9e85d0, 0x2a, 0xc006f84000, 0xc00e04a8c0)
        /home/ec2-user/go/src/github.com/harmony-one/harmony/api/service/explorer/storage.go:122 +0x159 fp=0xc0127ddc08 sp=0xc0127ddac0 pc=0x100b6d9
github.com/harmony-one/harmony/api/service/explorer.(*Storage).UpdateTxAddress(0xc0003f0040, 0xc006f84000, 0xc00e04a8c0)
        /home/ec2-user/go/src/github.com/harmony-one/harmony/api/service/explorer/storage.go:105 +0xa8 fp=0xc0127ddc48 sp=0xc0127ddc08 pc=0x100b3e8
github.com/harmony-one/harmony/api/service/explorer.(*Storage).Dump(0xc0003f0040, 0xc013c36a80, 0xc2b)
        /home/ec2-user/go/src/github.com/harmony-one/harmony/api/service/explorer/storage.go:89 +0xcf fp=0xc0127ddcc8 sp=0xc0127ddc48 pc=0x100b21f