Fix is underway: https://codereview.chromium.org/2555213005/

This needs to be merged to M56.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/00c82cd1badfcce85b1f12523b27e10392414fbf

commit 00c82cd1badfcce85b1f12523b27e10392414fbf
Author: yangguo <yangguo@chromium.org>
Date: Thu Dec 08 08:14:49 2016

[serializer] fix hash function for hashmap used for serializing.

Yes. I thought I was being smart. And yes. It's just a one-liner.

TBR=cbruni@chromium.org
BUG= chromium:672009 

Review-Url: https://codereview.chromium.org/2555213005
Cr-Commit-Position: refs/heads/master@{#41572}

[modify] https://crrev.com/00c82cd1badfcce85b1f12523b27e10392414fbf/src/address-map.h

Your change meets the bar and is auto-approved for M56 (branch: 2924)

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/021f8d3774d033cd47f282de4f857e0ef7e0e658

commit 021f8d3774d033cd47f282de4f857e0ef7e0e658
Author: Yang Guo <yangguo@chromium.org>
Date: Fri Dec 09 08:15:10 2016

Merged: [serializer] fix hash function for hashmap used for serializing.

Revision: 00c82cd1badfcce85b1f12523b27e10392414fbf

BUG= chromium:672009 
LOG=N
NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true
TBR=cbruni@chromium.org

Review-Url: https://codereview.chromium.org/2566643002 .
Cr-Commit-Position: refs/branch-heads/5.6@{#49}
Cr-Branched-From: bdd3886218dfe76e8560eb8a18401942452ae859-refs/heads/5.6.326@{#1}
Cr-Branched-From: 879f6599eee6e1dfcbe9a24bf688b261c03e9558-refs/heads/master@{#41014}

[modify] https://crrev.com/021f8d3774d033cd47f282de4f857e0ef7e0e658/src/address-map.h

I can still see very large pauses no the second load when keep several tabs open in chrome.
A good run:
[Serializing to 61241280 bytes took 1045.540 ms]
[Compiling and serializing took 3046.946 ms]

Bad run:
[Serializing to 61241280 bytes took 45486.185 ms]
[Compiling and serializing took 47333.635 ms]

For this particular case the hash function really runs hot. We are spending around 16% of the time in the hash table to lookup whether we already serialized a particular object. Changing the hash function would fix this particular edge case, but also make any other serialization slower.

This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

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This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

If all merges have been completed, please remove any remaining Merge-Approved labels from this issue.

Thanks for your time! To disable nags, add the Disable-Nags label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot