Reduce MutableProxy per-element overhead and cache per-field proxies by Alek99 · Pull Request #6740 · reflex-dev/reflex

Alek99 · 2026-07-10T20:03:48Z

Description

MutableProxy._wrap_recursive walked 5 stack frames (_is_called_from_dataclasses_internal) for every element retrieved through a proxy, before the cheap is_mutable_type check that usually decides nothing needs wrapping. The checks are reordered so immutable elements (the common case: ints, strings in a proxied list) skip the frame walk entirely. The dataclasses-internal check still runs for mutable values, preserving dataclasses.asdict/astuple behavior.
BaseState._get_attribute constructed a fresh MutableProxy on every read of a mutable state var. The proxy is now cached per instance and field name, invalidated by identity when the underlying value is reassigned. The cache is excluded from pickling (__getstate__), and copy/deepcopy already round-trip through __getstate__, so copies never share or carry proxies.

One deliberate nuance: when _wrap_recursive receives an already-proxied value and is called from dataclasses internals, it now returns the unwrapped value (previously the still-wrapped proxy), matching the documented intent of that path.

Benchmarks (GitHub Actions runner, run, 2 passes each)

Case	main	this PR	speedup
iterate 1000-int list via proxy	0.977 / 0.973 ms	0.219 / 0.214 ms	~4.5x
index 1000 elements via proxy	1.204 / 1.171 ms	0.396 / 0.381 ms	~3.0x
read mutable var attribute	2.82 / 2.87 us	1.17 / 1.15 us	~2.4x

cProfile (20 iterations + 2000 attr reads): _is_called_from_dataclasses_internal (20,000 calls, 0.028s cumulative) disappears from the profile; total function calls drop from 168k to 72k.

Type of change

Bug fix (non-breaking change which fixes an issue)

Changes To Core Features:

Have you added an explanation of what your changes do and why you'd like us to include them?
Have you written new tests for your core changes, as applicable?
- tests/units/istate/test_proxy.py: proxy reused across reads and invalidated on reassignment; cache never serialized (pickle round-trip rebinds proxies to the restored state); iteration yields plain immutables while mutable elements stay wrapped.
Have you successfully ran tests with your changes locally?

🤖 Generated with Claude Code

https://claude.ai/code/session_01G8cXh3TUbNtbjm2ERqE62X

Generated by Claude Code

linear-code · 2026-07-10T20:03:51Z

ENG-10094

greptile-apps · 2026-07-10T20:05:46Z

Greptile Summary

This PR reduces overhead in state proxying, memo compilation, validation, and websocket updates. The main changes are:

Cached per-field mutable state proxies with reassignment invalidation.
Faster MutableProxy wrapping for immutable values.
Deduplicated passthrough memo definitions during compilation.
Faster deterministic component hashing and memo tag generation.
Shallower diagnostic type checks on hot state paths.
Direct websocket update emits with an explicit event-loop yield.
Performance news entries and tests for the changed paths.

Confidence Score: 5/5

This looks safe to merge.

No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
reflex/state.py	Adds a non-serialized mutable proxy cache and invalidates cached proxies when state fields are reassigned.
reflex/istate/proxy.py	Skips dataclasses frame inspection for immutable values while preserving mutable-value wrapping behavior.
packages/reflex-base/src/reflex_base/components/memo.py	Computes passthrough memo tags before body construction and reuses matching memo definitions from the compile registry.
reflex/compiler/plugins/memoize.py	Moves passthrough memo registration into the shared memo creation path and only rewrites event triggers when a new body is built.
reflex/compiler/utils.py	Compiles passthrough memo bodies using the prebuilt children hole instead of swapping children during render.
packages/reflex-base/src/reflex_base/utils/types.py	Adds environment-sensitive validation depth for hot-path state type checks.
packages/reflex-base/src/reflex_base/vars/base.py	Runs computed-var return-type checks only when cached values are recomputed.
reflex/app.py	Replaces the awaited emit task wrapper with a direct emit and an explicit loop tick.

_{Reviews (5): Last reviewed commit: "Declare _mutable_proxy_cache as a reserv..." | Re-trigger Greptile}

codspeed-hq · 2026-07-10T20:06:22Z

Merging this PR will improve performance by ×3.2

⚠️

Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 2 improved benchmarks
✅ 25 untouched benchmarks
⏩ 8 skipped benchmarks¹

Performance Changes

	Benchmark	`BASE`	`HEAD`	Efficiency
⚡	`test_var_access[mutable_list]`	71.1 ms	19.1 ms	×3.7
⚡	`test_var_access[mutable_dict]`	88.4 ms	32.6 ms	×2.7

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

_{Comparing claude/reflex-perf-optimizations-01l7a3-eng-10094 (01ec207) with claude/reflex-perf-optimizations-01l7a3-eng-10093 (1b480cb)}

8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

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masenf · 2026-07-14T00:28:01Z

        ):
            # track changes in mutable containers (list, dict, set, etc)
-            return MutableProxy(wrapped=value, state=self, field_name=name)
+            cache = super().__getattribute__("__dict__").get("_mutable_proxy_cache")


similar to the last PR, unclear on why these cache flags are being directly added into the __dict__ and using object.__setattr__ and the like instead of just defining them as reserved fields on the state.

if we define them as real fields on the state, then users will get an exception if they try to reuse the name, instead of internal tracking machinery just getting broken or corrupting user data.

Good call — converted in d6ab47c: _mutable_proxy_cache is now a declared field(default_factory=dict, is_var=False) like _backend_vars/_was_touched, added to RESERVED_BACKEND_VAR_NAMES so a user var with that name can't silently collide. It stays out of pickles (__getstate__ pop) and is recreated empty in __setstate__. I'll apply the same treatment to the propagation-frontier fields in #6743.

Generated by Claude Code

_wrap_recursive walked 5 stack frames (dataclasses-internal check) for every element retrieved through a proxy, even immutable scalars that never get wrapped. Check is_mutable_type first so immutable elements skip the frame walk entirely. Also cache the MutableProxy built for each mutable state var on the instance, keyed by field name, instead of constructing a fresh proxy on every attribute read. The cache is invalidated by identity when the underlying value is reassigned and is excluded from pickling (copy and deepcopy already go through __getstate__). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01G8cXh3TUbNtbjm2ERqE62X

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01G8cXh3TUbNtbjm2ERqE62X

Address review feedback: drop the _mutable_proxy_cache entry when a base or backend var is assigned, so the replaced value is not kept alive by the cached proxy until the next read. Update test_set_base_field_via_setter for the new cached-proxy identity semantics. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01G8cXh3TUbNtbjm2ERqE62X

Address review feedback: instead of managing the proxy cache as an ad-hoc instance __dict__ entry, declare it as a real (non-var) field like _backend_vars/_was_touched and add it to RESERVED_BACKEND_VAR_NAMES, so user vars cannot silently collide with the framework's tracking machinery. The cache is still excluded from pickling and recreated empty on unpickle. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01G8cXh3TUbNtmC37Y8kJ5S6

Alek99 requested a review from a team as a code owner July 10, 2026 20:03

chatgpt-codex-connector Bot reviewed Jul 10, 2026

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Comment thread reflex/state.py Outdated

masenf requested changes Jul 14, 2026

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claude added 4 commits July 17, 2026 18:44

Add changelog fragment

a36bfa9

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01G8cXh3TUbNtbjm2ERqE62X

Alek99 force-pushed the claude/reflex-perf-optimizations-01l7a3-eng-10094 branch from d6ab47c to 01ec207 Compare July 18, 2026 01:46

Alek99 changed the base branch from main to claude/reflex-perf-optimizations-01l7a3-eng-10093 July 18, 2026 01:46

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Reduce MutableProxy per-element overhead and cache per-field proxies#6740

Reduce MutableProxy per-element overhead and cache per-field proxies#6740
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Alek99 commented Jul 10, 2026

Description

Benchmarks (GitHub Actions runner, run, 2 passes each)

Type of change

Changes To Core Features:

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Greptile Summary

Confidence Score: 5/5

Important Files Changed

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Merging this PR will improve performance by ×3.2

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