# Arbitrum Odyssey为什么暂停

By [luxebeng](https://paragraph.com/@luxebeng) · 2022-07-07

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Arbitrum Odyssey暂停的猜想
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在6月29日，Arbitrum因为Gas Price暴涨，暂停了Odyssey活动。

![Arbitrum GasFee at 29th June](https://storage.googleapis.com/papyrus_images/420a44d3112c43cb2af1f3616030af8256c671a5cf03750be9e68c427949a8f8.png)

Arbitrum GasFee at 29th June

这件事的导火索是由于GMX突然提高了它的APP的Gas费。当然GMX说提高Gas费是正常举动。它的直接后果就拉高了Arbitrum链上的Gas平均水平。网上对Arbitrum的批评声不绝于耳，因为这件事确实让L2技术变成一个笑话。

大家都知道QoS。如果在网络拥塞的情况下，单纯的提高Priority并不能解决问题。这件事即使GMX是始作俑者，但是不是根本原因。系统的性能瓶颈才是症结所在。

Gas计算
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这是从Arbitrum官方文档中找到的一段关于ArbGas的计算方法，可以看到，当网络出现拥塞的时候，ArbGas就会不断增加。其是希望通过提高GasFee从而达到网络的动态平衡。

    **Price for ArbGas**
    > ArbGas pricing depends on a minimum price, and a congestion pricing mechanism.
    
    > The minimum ArbGas price is set equal to the estimated L1 gas price divided by 100. The price of ArbGas will never go lower than this.
    
    > The price will rise above the minimum if the chain is starting to get congested. The idea is similar to Ethereum, to deal with a risk of overload by raising the price of gas enough that demand will meet supply. The mechanism is inspired by Ethereum’s EIP-1559, which uses a base price that, at the beginning of each block, is multiplied by a factor between 7/8 and 9/8, depending on how busy the chain seems to be. When the demand seems to be exceeding supply, the factor will be more than 1; when supply exceeds demand, the factor will be less than 1. (But the price never goes below the minimum.)
    
    > The automatic adjustment mechanism depends on an “ArbGas pool” that is tracked by ArbOS. The ArbGas pool has a maximum capacity that is equal to 12 minutes of full-speed computation at the chain’s speed limit. ArbGas used by transactions is subtracted from the gas pool, and at the beginning of each new Ethereum block, ArbGas is added to the pool corresponding to full-speed execution for the number of timestamp seconds since the last block (subject to the maximum pool capacity).
    
    > After adding the new gas to the pool, if the new gas pool size is G, the current ArbGas price is multiplied by (16200S - G) / (14400S) where S is the ArbGas speed limit of the chain. This quantity will be 7/8 when G = 720S (the maximum gas pool size) and it will be 9/8 when G = 0.
    

大家的一个疑问是，Arbitrum链出现拥塞的ThreshHold也太低了吧。

今天Arbitrum官方宣布正式发布Nitro(参考链接[It’s Nitro time](https://medium.com/offchainlabs/its-nitro-time-86944693bf29))。现在也理解项目方为什么有底气突然停止Odyssey的活动，那是因为Nitro已经基本就绪了。所以才暂停Odyssey一两周的时间。如下是这个消息中关于Nitro，可以极大提高Arbitrum链的处理能力。当然这个还有待检验。

    I’m glad you asked. **Nitro will massively increase network capacity** and reduce transaction costs. Today, we throttle Arbitrum’s capacity, but with Nitro we’ll be able to release those controls and significantly up our throughput. And while Arbitrum today is already 90–95% cheaper than Ethereum on average, Nitro cuts our costs even further.
    

可能的问题
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那我们回头再来测测一下Arbitrum One可能在哪儿出现瓶颈了。

*   L2 Arbitrum engine
    

按照目前的说法，它有一套私有的语言和编译器。为了和EVM兼容，Arbitrum运行一个内嵌的EVM仿真器，对所有的EVM代码，都会有一个built-in complier，对EVM的指令逐条翻译。像当初很多虚拟机一样，速度慢。所以Nitro声称现在L2 Arbitrum engine已经通过WASM实现直接编译Geth进Arbitrum，所以速度很提升很多。

*   ArbOS内部实现臃肿
    

ArbOS也许生成的东西比较臃肿导致calldata比较大，所以不论L2 Tx还是L1 Tx，Cost都比较大。没有能够很好的实现Batching和Compression。虽然这个在官方文档中被说成Arbitrum的优点：[Full Node of Arbitrum](https://developer.offchainlabs.com/docs/inside_arbitrum#full-nodes)

*   Sequencer
    

这个组件是Arbittrum的开发公司Offchain Labs自己维护的。作为一个特别的Full Node，它是所有的Client和Arbitrum的接口，负责把所有的消息打包进入Arbitrum的Inbox队列。它是目前系统中一个中心化的节点，而且没有看到关于它的性能介绍。它的性能对系统的整体性能影响巨大。

*   Arbitrum One特殊设置
    

也许出于稳定性的需求，项目组在Arbitrum One 中在对软件Capacity做了一些约束。这些设置导致了GasFee在超出Capacity之后飙升。那么在接下来的Nitro，这些限制将被取消。按照Nitro的说法，Nitro会在更个模块都有优化。

    Nitro will massively increase network capacity and reduce transaction costs. Today, we throttle Arbitrum’s capacity, but with Nitro we’ll be able to release those controls and significantly up our throughput.
    

结论
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这次GasFee高的根本原因肯定是Arbitrum。从架构来看，这些问题更可能是Arbitrum实现过程中，很多特性没有实现，所以导致和预想的不一致。希望随着Arbitrum Nitro的推出，这个问题能够得到很好的解决。

参考文档
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[人为“调高GAS费”创收？Arbitrum Odyssey上GMX遭质疑](https://www.odaily.news/post/5179866)

[Inside Arbitrum](https://developer.offchainlabs.com/docs/inside_arbitrum)

[It’s Nitro time](https://medium.com/offchainlabs/its-nitro-time-86944693bf29)

[Compression in Nitro](https://research.arbitrum.io/t/compression-in-nitro/20)

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*Originally published on [luxebeng](https://paragraph.com/@luxebeng/arbitrum-odyssey)*