New Project Proposal: The Block GC

Mrinal Kanti mrinal.kanti at
Sun Apr 1 18:04:08 UTC 2018

May I suggest to throw in some crypto-mining code which could run while the
sysadmins and monitoring agents are under the impression that its the GC
behavior that's being optimized under the hood. Farms of enterprise server
clusters couldn't have been better utilized. Definitely sounds more
efficient than the browser plugin approach.

On Sun, Apr 1, 2018 at 1:05 PM, Magnus Ihse Bursie <
magnus.ihse.bursie at> wrote:

> I hereby propose the creation of the Block GC Project with myself (Magnus
> Ihse Bursie) as the Lead and the Build Group as the sponsoring group.
> In accordance with the OpenJDK guidelines [1], this project will provide
> the Block GC, a creative new approach of handling GC mis-optimization.[2]
> The Block GC, also known as the Block Chain GC, is an innovative new
> system for Garbage Collection. It is a well-known fact that even though the
> JVM can be fine-tuned to employ an optimal GC method for a specific
> payload, most users do not bother to do so, or lack the technical skills
> needed to select the proper GC. The Block GC is a "parasitic" GC, in that
> it does not provide a separate GC system of it own, but instead selects the
> most optimal GC for each individual payload.
> As a unique feature, the Block GC will measure and accurately calculate
> the improvement provided by selecting the optimal GC method, compared to
> the GC previously selected. Let T_gc_def be the time the user application
> is stopped during the GC for the default GC settings, and let T_gc_opt be
> the corresponding time using the optimal GC method selected by the Block
> GC. The difference T_gc_def - T_gc_opt is the improvement in pausetime
> provided by the Block GC, and is known as the "block gain".
> The block gain can be seen as a hidden resource, available for free from
> the user of the JRE. After the GC has finished, the JRE can use the time
> provided by the block gain, with the user threads still suspended, without
> the application suffering performance regressions. In the initial
> implementation of the Block GC, the block gain was just used to let the JVM
> sleep for an amount of time corresponding to the block gain. This gave us a
> simple way to save processor cycles, and hence energy, thus providing a
> simple way for the Java user to help fight climate change without even
> noticing it.
> While a noble goal, this does not really makes business sense. In the
> updated version of the Block GC, which we propose to be added as the
> default GC in JDK 11, the block gain is instead used to calculate hash
> values for popular cryptocurrencies, a.k.a. "bitcoin mining". Our estimates
> show that this can generate a significant amount of revenue; with a
> projected ~50 M downloads of JDK 11, running typical workloads, and with
> typical values for GC settings (default or misconfigured), $50k/day for all
> OpenJDK installations worldwide is not unreasonable.
> This is a pure win-win scenario. The user will not notice any performance
> regression compared to the previous GC settings, and the cryptocurrency
> account proprietor will benefit fiscally.
> The user can set their own blockchain account, instead of the default, by
> issuing this command:
>    java -XX:UnlockDangerousOptions -XX:UnsupportedGCOption=new_provider_config:<path
> to config file>
> where <path to config file> points to a configuration file in ASN.1 format
> describing the blockchain account. We hope to finish the documentation of
> this file in time for the release, but if not done, it will not be
> considered a release blocker.
> If a user override is not provided as above, by default, the revenue
> extracted by the Block GC miner will be stored in the Block GC Project
> account. This revenue will be divided as follows: 90% will go to the
> initial committers of the Block GC Project, and 10% will go to the OpenJDK
> community.
> The first installment of the 10% payment to the OpenJDK comminuty will be
> issued exactly one year from now, on April 1st 2019.[3]
> A preview of the Block GC can be found here:
> The initial Committers will be: Magnus Ihse Bursie, Satoshi Nakamoto and
> P. T. Barnum.
> /Magnus
> [1]
> [2]
> [3]

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