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tip: 362
title: Optimized node broadcast data caching
author: forfreeday@163.com
discussions to: https://github.com/tronprotocol/TIPs/issues/348
status: Final
type: Standards Track
category: Core
created: 2022-01-17

Simple Summary

The node caches a large amount of transaction data before broadcasting, and as a way to determine whether the transaction is duplicated, the default cache is 100_000 effect easy to ensure that there will be no duplicate transactions. And this part of the transaction in actual use found that caching 100_000 transactions, will occupy a lot of memory space, and there are many redundant objects, these cache occupies a lot of occupied memory.

Abstract

Optimize the cache size of transaction broadcasts to save memory space occupied by broadcast transactions.

In tron's network node, the broadcast transactions to be sent are cached in the current local cache. The default cache size is currently set to 100_000. Both caches are used in practice, and data is added to the cache but not immediately cleared. Too many objects will occupy the memory space of JVM.

It is possible to optimize some of the JVM recycling.

Using guavaCache as a cache, the elimination policy is used, and the elimination mechanism will be unlocked only when the cache is filled. In other words, 100000 Iterm, Long KV objects will be cached in memory all the time. This is a waste of memory, and the number of objects cached in memory can actually be reduced to save memory space.

Motivation

Reduce expired cache footprint and boost more memory space

Implementation

Two important caches.

  1. advInvReceive: cache of incoming inv messages
  2. advInvSpread: cache of sent inv messages

The current default cache size is 100_000, adjust this cache size. These two caches are in actual use, data is added to the cache but not immediately cleared. Too many objects will take up memory space in the JVM.

It is possible to optimize some of the JVM recycling.

The guavaCache is used as a cache and uses a phaseout policy, where the phaseout mechanism is unlocked only when the cache is filled. This means that 100000 Iterm, Long KV objects will be cached in memory all the time. This is a waste of memory, and the number of objects cached in memory can actually be reduced to save memory space.

Rationale

JVM overview and memory usage when cache is 100_000

cache instance: 1310237 Memory Usage: 41927584 bytes

  10:       1310237       41927584  org.tron.core.net.peer.Item
 252:            27           4968  org.tron.core.net.peer.PeerConnection
2556:             1             24  org.tron.core.net.peer.PeerStatusCheck
3496:             1             16  org.tron.core.net.peer.PeerStatusCheck$$Lambda$411/507363919

The local cache relies on GuavaCache, and the reduction of objects largely reduces the number of cached objects created by GuavaCache. GuavaCache caches an object by constructing a series of objects based on the ReferenceEntry interface.

4:       2345662      150122368  com.google.common.cache.LocalCache$StrongAccessWriteEntry
10:       2345862       37533792  com.google.common.cache.LocalCache$StrongValueReference
108:           381          30480  com.google.common.cache.LocalCache$Segment
168:            96          12288  com.google.common.cache.LocalCache187:           
200           9600  com.google.common.cache.LocalCache$StrongAccessEntry
195:           381           9144  com.google.common.cache.LocalCache$AccessQueue$1226:           
265           6360  com.google.common.cache.LocalCache$WriteQueue$1

Most of the objects cached by Guave cache will be held cached in the new generation, and the usage of the new generation space will always be high.

Heap Usage:
New Generation (Eden + 1 Survivor Space):
   capacity = 2899116032 (2764.8125MB)
   used     = 2630018496 (2508.1810913085938MB)
   free     = 269097536 (256.63140869140625MB)
   90.7179452967821% used

JVM overview and memory usage when cache is 20_000

  11:        504003       16128096  org.tron.core.net.peer.Item
 252:            30           5520  org.tron.core.net.peer.PeerConnection
2605:             1             24  org.tron.core.net.peer.PeerStatusCheck
3539:             1             16  org.tron.core.net.peer.PeerStatusCheck$$Lambda$411/757310910

After the adjustment, GuavaCache also requires 50% fewer objects to build the cache

6:         1145849       73334336  com.google.common.cache.LocalCache$StrongAccessWriteEntry 
10:        1146053       18336848  com.google.common.cache.LocalCache$StrongValueReference
102:           417          33360  com.google.common.cache.LocalCache$Segment
164:           105          13440  com.google.common.cache.LocalCache188:           
417          10008  com.google.common.cache.LocalCache$AccessQueue$1192:           
204           9792  com.google.common.cache.LocalCache$StrongAccessEntry230:           
289           6936  com.google.common.cache.LocalCache$WriteQueue$1

50% improvement in memory space for the new generation compared to pre-optimization

New Generation (Eden + 1 Survivor Space):
   capacity = 2899116032 (2764.8125MB)
   used     = 1315915376 (1254.9546966552734MB)
   free     = 1583200656 (1509.8578033447266MB)
   45.39022796863344% used