What a fast local loop can do?

[Denis Garsh]

Introduction

The purpose of this document is to show what speed up we can have when optimizing operations with local variables in rholang.
This work related with two documents:

• #3607
• #3700

Now each sending and receiving operation in Rholang is saved in the eventLog:

But for data processing, we can avoid local operations, as shown below.

But we need to learn how to detect local operations. This question is open.

Why need to avoid saving local values in the eventLog?

Because it's slow. We need to spend time for:

• Serializing;
• Hashing;
• Sorting;
• Refunding (We must refund the full cost for matched com events);

Also we need spend time and disc space to save in BlockStore and sending to the validators.

We can optimize the operations in the reducer (see the red and green entries in the picture below). But it still won't do much good for data processing.

Experimental results

Performance tests:
b5285b7
1 optimization step: removing serialization from charging:
93e416a
2 optimization step for Int: remove substituting and evaluating from List
No change
2 optimization step for List: remove substituting and evaluating from List
29f5c8c
2 optimization step for Map: optimization of Map
29f5c8c
3 optimization step: remove looping from eventLog
44ef594

Sum of Ints

for( @n, @x <= @"loop" ) {
  match (n == 0) {
    true  => @"$outcomeCh"!(x)
    false => @"loop"!((n - 1), x + n)
  }  
}  

Num	Init	1 step: removing serialization from charging	3 step: remove looping from eventLog
100	882	839	369
200	999	927	437
300	1046	924	286
400	1026	937	277
500	1338	1219	253
600	1281	1304	296
700	1325	1147	212
800	1461	1129	223
900	1561	1213	245
1000	1578	1297	256
1100	1757	1437	280
1200	1833	1441	311
1300	2001	1540	325
1400	2190	1636	346
1500	2318	1805	372
1600	2575	1987	418
1700	2618	2088	391
1800	2740	2225	401
1900	2805	2334	463
2000	2957	2423	468

Append in List

@"loop"!($numberElements, []) |
for( @n, @x <= @"loop" ) {
  match (n == 0) {
    true  => @"$outcomeCh"!(x)
    false => @"loop"!((n - 1), x ++ [1])
  }  
}  

Num	Init	1 step: removing serialization from charging	2 step: remove substituting and evaluating from List	3 step: remove looping from eventLog
100	1220	1316	923	401
200	1985	2521	1358	583
300	3443	3384	2387	420
400	6669	5889	3386	295
500	9898	8340	5115	261
600	13218	11495	7171	432
700	16926	15465	9649	250
800	22879	21679	11392	276
900	27612	28086	14510	311
1000	32345	35621	16901	327

Append in Map

@"loop"!($numberElements, {}) |
for( @n, @x <= @"loop" ) {
  match (n == 0) {
    true  => @"$outcomeCh"!(x)
    false => @"loop"!((n - 1), x.set(n,n))
  }  
}  

Num	Init	1 step: removing serialization from charging	2 step: optimization of Map	3 step: remove looping from eventLog
100	3489	3006	1692	604
200	10377	9264	3660	558
300	24632	19869	6896	479
400	46370	35158	11343	429
500	67139	54624	17394	463
600	107936	78667	24792	546

Conclusions

If we want Rholang to be used for data processing, we must optimize the work with local variables. Otherwise, it is justified to use Rholang as an intermediate layer between the user program and storage.

Because when we drawing a cat:

We save all intermediat result in blockChain.