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fix: Update resource limits #374

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schneiderstefan merged 1 commit into from
Aug 31, 2026
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fix: Update resource limits #374

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20 changes: 11 additions & 9 deletions docs/references/resource-limits.md
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ ICP uses WebAssembly as the execution environment for canisters. Because WebAsse
| Limit | Value |
|-------|-------|
| Message queue limit (between a canister pair) | 500 |
| Max ingress message payload | 2 MiB |
| Max ingress message payload | 2 MiB (3.5 MiB on the NNS subnet) |
| Max cross-subnet inter-canister message payload | 2 MiB |
| Max same-subnet inter-canister request payload | 10 MiB |
| Max response size (replicated execution) | 2 MiB |
Expand All @@ -26,7 +26,7 @@ ICP uses WebAssembly as the execution environment for canisters. Because WebAsse
| Per query call | 5 billion |
| Per canister install or upgrade | 300 billion |
| Per `inspect_message` | 200 million |
| Per round per execution thread | 7 billion |
| Per round per execution thread | 4 billion |

## Memory limits

Expand All @@ -38,15 +38,17 @@ ICP uses WebAssembly as the execution environment for canisters. Because WebAsse
| Stable memory written per replicated message | 2 GiB |
| Stable memory read per upgrade message | 8 GiB |
| Stable memory written per upgrade message | 8 GiB |
| Stable memory read per replicated query | 1 GiB |
| Stable memory written per replicated query | 1 GiB |
| Stable memory read per query call | 1 GiB |
| Stable memory written per query call | 1 GiB |

The query limits apply to every query type: non-replicated, replicated, and composite queries, as well as `inspect_message`.

## Wasm module limits

| Limit | Value |
|-------|-------|
| Wasm total size per canister | 100 MiB |
| Wasm code section per canister | 10 MiB |
| Wasm code section per canister | 12 MiB |
| Custom sections per subnet | 2 GiB |
| Custom sections per canister | 1 MiB |
| Custom section count per canister | 16 |
Expand All @@ -72,13 +74,13 @@ ICP uses WebAssembly as the execution environment for canisters. Because WebAsse

| Limit | Value |
|-------|-------|
| Environment variables per canister | 20 |
| Environment variables per canister | 32 |
| Variable name length | 128 bytes |
| Variable value length | 128 bytes |

## Performance characteristics

Block production rate varies from 0.75 to 1.5 blocks per second depending on [subnet](../concepts/network-overview.md#subnets) load and node count. Up to 1,000 messages can be included in a block. Because ICP decouples message reception from message execution, messages included in a block are not guaranteed to execute in the same block. Messages for different canisters may execute in parallel across up to 4 execution threads, each capable of handling up to 1,000 messages. ICP targets a throughput of 2 billion Wasm instructions per thread per second.
Block production rate varies from 1 to 3 blocks per second depending on [subnet](../concepts/network-overview.md#subnets) load and node count. Up to 1,000 messages can be included in a block. Because ICP decouples message reception from message execution, messages included in a block are not guaranteed to execute in the same block. Messages for different canisters may execute in parallel across up to 4 execution threads. ICP targets a throughput of 2 billion Wasm instructions per thread per second.

## Additional notes

Expand All @@ -90,8 +92,8 @@ The IC rejects Wasm modules that exceed these structural limits:
- More than 1,000 declared globals
- A function body containing more than 1,000,000 Wasm instructions
- More than 16 exported custom sections (names prefixed with `icp:`)
- More than 1,000 exported `canister_update <name>` or `canister_query <name>` functions
- Combined `<name>` lengths across all exported update and query functions exceeding 20,000 characters
- More than 1,000 exported `canister_update <name>`, `canister_query <name>`, or `canister_composite_query <name>` functions
- Combined `<name>` lengths across all exported update, query, and composite query functions exceeding 20,000 characters
- Total exported custom sections size exceeding 1 MiB

For the full specification of these constraints, see [WebAssembly module requirements](ic-interface-spec/canister-interface.md#system-api-module).
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