fix(bulk load): panic: z.Buffer max size exceeded

[JoelWesleyReed]

(stack trace from release v21.12.0)

panic: z.Buffer max size exceeded: 68719476736 offset: 68719476724 grow: 50

goroutine 12167 [running]:
github.com/dgraph-io/ristretto/z.(*Buffer).Grow(0xc02c4a4000, 0x32)
	/go/pkg/mod/github.com/dgraph-io/[email protected]/z/buffer.go:180 +0x56e
github.com/dgraph-io/ristretto/z.(*Buffer).SliceAllocate(0xc02c4a4000, 0x2e)
	/go/pkg/mod/github.com/dgraph-io/[email protected]/z/buffer.go:266 +0x2e
github.com/dgraph-io/dgraph/dgraph/cmd/bulk.(*mapIterator).Next(0xc027cfaf60, 0xc02c4a4000, {0xc00378fd00, 0x1f, 0x20})
	/ext-go/1/src/github.com/dgraph-io/dgraph/dgraph/cmd/bulk/reduce.go:206 +0x127
github.com/dgraph-io/dgraph/dgraph/cmd/bulk.(*reducer).reduce.func2()
	/ext-go/1/src/github.com/dgraph-io/dgraph/dgraph/cmd/bulk/reduce.go:488 +0x5cd
created by github.com/dgraph-io/dgraph/dgraph/cmd/bulk.(*reducer).reduce
	/ext-go/1/src/github.com/dgraph-io/dgraph/dgraph/cmd/bulk/reduce.go:478 +0x465

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[mangalaman93]

@JoelWesleyReed if you are still interested in merging this change, could you rebase on latest main please and sign the CLA? Thanks

[davideaimar]

I encountered the same problem trying to bulk import a huge dataset and this PR fixed the max size panic. Is it possible to merge it? Otherwise @mangalaman93 I can open a new PR.

[mangalaman93]

Yeah, you'll have to cherry pick your changes on main instead of master. You should still be able to force push to the same branch. You are welcome to create another PR too.

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