perf!: serialize requests once in batchAddRequests by vdusek · Pull Request #1051 · apify/apify-client-js

vdusek · 2026-09-09T09:38:52Z

Description

Mirroring fix: Make batch_add_requests split batches by serialized payload size apify-client-python#953.
batchAddRequests stringified every request twice: once in sliceArrayByByteLength to measure the batch, and again in the serializeRequest interceptor when sending. Axios then ran its default transformRequest on top, because transformRequest: undefined in the instance config falls back to the defaults, and that default validates a JSON string body by parsing it in full. Each batch body was stringified twice and parsed once more.
Each request is now serialized once up front. The byte lengths decide the batch boundaries (commas and brackets counted, which the old measurement skipped) and the same strings are joined into the batch body, sent with an explicit content-type: application/json. The interceptor passes a string body with an explicit content type through untouched, and the axios instance sets transformRequest and transformResponse to []. That also removes the validation re-parse for every JSON body the client sends.

Issue

Closes Avoid double JSON serialization in batchAddRequests #972

Breaking changes

A string body declared as JSON but not valid JSON (for example setRecord with contentType: 'application/json' and a non-JSON string) is sent as it is. Axios used to double-encode it into a JSON string literal.
A request too large for the payload limit is rejected before any batch is sent. It used to be detected only when its batch came up, with earlier batches already in flight.
The protected _batchAddRequests and _batchAddRequestsWithRetries take the serialized entries, and _batchAddRequests no longer re-validates a batch the public method already validated. The API report is updated.

✍️ Drafted by Claude Code

github-actions · 2026-09-09T09:40:25Z

⚠️ There are broken links in the documentation.

See more at https://github.com/apify/apify-client-js/actions/runs/34862046980#summary-104036487629

…patch

…-single-serialization

…ing guide

…ng changes

…-single-serialization

…-single-serialization # Conflicts: # docs/04_upgrading/upgrading_v3.md # docs/public-api/apify-client.api.md # src/resource_clients/request_queue.ts # test/http_client.test.ts

…-single-serialization # Conflicts: # src/resource_clients/request_queue.ts

barjin

Just some nits / thinking out loud, otherwise lgtm.

Thanks @vdusek !

barjin · 2026-09-14T12:45:37Z

+
+A string body sent with an explicit `application/json` content type now goes out verbatim. Axios used to parse it to check that it was valid JSON, and wrapped it in a JSON string literal when it wasn't. The client skips that step so that `batchAddRequests()` can send a body it has already serialized.
+
+<ApiLink to="class/KeyValueStoreClient#setRecord">`setRecord()`</ApiLink> is where you'd notice. Storing a non-JSON string under `contentType: 'application/json'` used to save `"my value"`, quotes included, and now saves `my value`, which <ApiLink to="class/KeyValueStoreClient#getRecord">`getRecord()`</ApiLink> can't parse back:


which getRecord() can't parse back

This is kinda annoying, but understandable.

I'm not sure whether we should automatically parse the KVS contents based on the content-type in the client, but that ship has sailed, I suppose.

Yeah, I'm merging this. However, feel free to start a follow-up Slack discussion about it. I'd probably lean toward dropping this automatic parsing of KVS records based on their content type, but I think it deserves a bit more investigation and discussion first with a broader audience (also #product-dev-tools channel). I opened a follow-up issue for it: #1067, and we should discuss it before the v3 release.

Adds a regression test for #277: `start()` with a `Buffer` input and `contentType: 'application/json'` sends the raw bytes, and the server gets the decoded JSON back. The bug itself is already gone on `v3`. `serializeBody()` from #1058 passes binary and string bodies through before it reaches `JSON.stringify`, and axios no longer re-serializes strings since #1051 set `transformRequest: []`. With the Buffer branch disabled, the new test fails with the `{ type: 'Buffer', data: [...] }` payload from the issue. Closes #277 *✍️ Drafted by Claude Code*

### Description - Mirroring apify/apify-client-python#953. - `batchAddRequests` stringified every request twice: once in `sliceArrayByByteLength` to measure the batch, and again in the `serializeRequest` interceptor when sending. Axios then ran its default `transformRequest` on top, because `transformRequest: undefined` in the instance config falls back to the defaults, and that default validates a JSON string body by parsing it in full. Each batch body was stringified twice and parsed once more. - Each request is now serialized once up front. The byte lengths decide the batch boundaries (commas and brackets counted, which the old measurement skipped) and the same strings are joined into the batch body, sent with an explicit `content-type: application/json`. The interceptor passes a string body with an explicit content type through untouched, and the axios instance sets `transformRequest` and `transformResponse` to `[]`. That also removes the validation re-parse for every JSON body the client sends. ### Issue - Closes #972 ### Breaking changes - A string body declared as JSON but not valid JSON (for example `setRecord` with `contentType: 'application/json'` and a non-JSON string) is sent as it is. Axios used to double-encode it into a JSON string literal. - A request too large for the payload limit is rejected before any batch is sent. It used to be detected only when its batch came up, with earlier batches already in flight. - The protected `_batchAddRequests` and `_batchAddRequestsWithRetries` take the serialized entries, and `_batchAddRequests` no longer re-validates a batch the public method already validated. The API report is updated. *✍️ Drafted by Claude Code*

Adds a regression test for #277: `start()` with a `Buffer` input and `contentType: 'application/json'` sends the raw bytes, and the server gets the decoded JSON back. The bug itself is already gone on `v3`. `serializeBody()` from #1058 passes binary and string bodies through before it reaches `JSON.stringify`, and axios no longer re-serializes strings since #1051 set `transformRequest: []`. With the Buffer branch disabled, the new test fails with the `{ type: 'Buffer', data: [...] }` payload from the issue. Closes #277 *✍️ Drafted by Claude Code*

perf: serialize requests once in batchAddRequests

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vdusek added the t-tooling Issues with this label are in the ownership of the tooling team. label Sep 9, 2026

vdusek self-assigned this Sep 9, 2026

vdusek added 2 commits September 9, 2026 12:07

test: assert batchAddRequests retries only the unprocessed requests

9a4e059

test: assert batchAddRequests rejects an oversized request before dis…

2255472

…patch

vdusek changed the title ~~perf: serialize requests once in batchAddRequests~~ perf!: serialize requests once in batchAddRequests Sep 9, 2026

vdusek added 3 commits September 9, 2026 14:04

Merge remote-tracking branch 'origin/v3' into perf/batch-add-requests…

36a514d

…-single-serialization

docs: document the batchAddRequests breaking changes in the v3 upgrad…

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…ing guide

docs: limit the batchAddRequests upgrading notes to the public breaki…

8b9cdea

…ng changes

vdusek requested a review from barjin September 9, 2026 12:19

vdusek marked this pull request as ready for review September 9, 2026 12:19

vdusek requested a review from szaganek as a code owner September 9, 2026 12:19

vdusek mentioned this pull request Sep 10, 2026

feat!: allow passing a custom HTTP client to ApifyClient #1058

Merged

vdusek added 3 commits September 10, 2026 16:51

Merge remote-tracking branch 'origin/v3' into perf/batch-add-requests…

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…-single-serialization

Merge remote-tracking branch 'origin/v3' into perf/batch-add-requests…

3e7bb1f

…-single-serialization # Conflicts: # docs/04_upgrading/upgrading_v3.md # docs/public-api/apify-client.api.md # src/resource_clients/request_queue.ts # test/http_client.test.ts

Merge remote-tracking branch 'origin/v3' into perf/batch-add-requests…

982ade6

…-single-serialization # Conflicts: # src/resource_clients/request_queue.ts

barjin approved these changes Sep 14, 2026

View reviewed changes

refactor: read the content type through getHeader in serializeRequest

8f87c03

vdusek mentioned this pull request Sep 14, 2026

Rethink getRecord() parsing records by content type #1067

Open

vdusek merged commit 2ca4b04 into v3 Sep 14, 2026
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vdusek deleted the perf/batch-add-requests-single-serialization branch September 14, 2026 15:48

vdusek mentioned this pull request Sep 14, 2026

Avoid double JSON serialization in batchAddRequests #972

Closed

This was referenced Sep 25, 2026

test: cover sending a Buffer Actor input as raw bytes #1078

Merged

serializeRequest performs JSON.stringify on a Buffer #277

Closed

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perf!: serialize requests once in batchAddRequests - #1051

perf!: serialize requests once in batchAddRequests#1051
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		A string body sent with an explicit `application/json` content type now goes out verbatim. Axios used to parse it to check that it was valid JSON, and wrapped it in a JSON string literal when it wasn't. The client skips that step so that `batchAddRequests()` can send a body it has already serialized.

		<ApiLink to="class/KeyValueStoreClient#setRecord">`setRecord()`</ApiLink> is where you'd notice. Storing a non-JSON string under `contentType: 'application/json'` used to save `"my value"`, quotes included, and now saves `my value`, which <ApiLink to="class/KeyValueStoreClient#getRecord">`getRecord()`</ApiLink> can't parse back:

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