perf: Skip request-body compression for already-compressed content types

docs/02_concepts/13_http_compression.mdx

@@ -1,15 +1,48 @@
 ---
 id: http-compression
 title: HTTP compression
-description: The client compresses every request body automatically using gzip by default, with optional brotli via an explicit opt-in.
+description: The client compresses request bodies automatically using gzip by default, with optional brotli via an explicit opt-in.
 ---
 
-The Apify client compresses every request body before sending it to the API. It reduces the amount of data transferred over the network, resulting in faster requests and lower bandwidth usage, especially for large payloads such as Actor inputs, dataset uploads, or key-value store records.
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+import CodeBlock from '@theme/CodeBlock';
+
+import SkipCompressionAsyncExample from '!!raw-loader!./code/13_skip_compression_async.py';
+import SkipCompressionSyncExample from '!!raw-loader!./code/13_skip_compression_sync.py';
+
+The Apify client compresses request bodies before sending them to the API. It reduces the amount of data transferred over the network, resulting in faster requests and lower bandwidth usage, especially for large payloads such as Actor inputs, dataset uploads, or key-value store records.
 
 ## How it works
 
 The client compresses request bodies using the compressor configured via the `compression` parameter (default `'gzip'`). The server supports both gzip and brotli and decompresses the request body transparently.
 
+## Already-compressed payloads
+
+Some payloads carry their own compression, so compressing them again costs CPU and memory while making the request slightly larger. The client skips compression when the request's `Content-Type` is one of these:
+
+- any `image/*`, `audio/*`, or `video/*` type
+- archives such as `application/zip`, `application/gzip`, or `application/x-7z-compressed`
+- office documents and packages built on ZIP, such as `.docx`, `.xlsx`, `.epub`, or `.apk`
+- web fonts (`font/woff`, `font/woff2`)
+
+Two kinds of media type are compressed anyway: raw formats such as `image/bmp`, `image/tiff`, and `audio/wav`, and subtypes with a structured syntax suffix such as `image/svg+xml`. Set an accurate `content_type` when uploading media to a key-value store:
+
+<Tabs>
+    <TabItem value="AsyncExample" label="Async client" default>
+        <CodeBlock className="language-python">
+            {SkipCompressionAsyncExample}
+        </CodeBlock>
+    </TabItem>
+    <TabItem value="SyncExample" label="Sync client">
+        <CodeBlock className="language-python">
+            {SkipCompressionSyncExample}
+        </CodeBlock>
+    </TabItem>
+</Tabs>
+
+Without an explicit content type, a `bytes` value is sent as `application/octet-stream`, which the client can't tell apart from uncompressed binary data and therefore still compresses. File-like values are streamed rather than buffered, so they're never compressed regardless of their content type.
+
 ## Configuration
 
 To choose the compression algorithm, pass `compression` to the client constructor:

docs/02_concepts/code/13_skip_compression_async.py

@@ -0,0 +1,20 @@
+import asyncio
+from pathlib import Path
+
+from apify_client import ApifyClientAsync
+
+TOKEN = 'MY-APIFY-TOKEN'
+
+
+async def main() -> None:
+    apify_client = ApifyClientAsync(TOKEN)
+    kvs_client = apify_client.key_value_store('MY-KVS-ID')
+
+    screenshot = await asyncio.to_thread(Path('screenshot.png').read_bytes)
+
+    # The explicit content type lets the client skip compressing the PNG.
+    await kvs_client.set_record('screenshot', screenshot, content_type='image/png')
+
+
+if __name__ == '__main__':
+    asyncio.run(main())

docs/02_concepts/code/13_skip_compression_sync.py

@@ -0,0 +1,15 @@
+from pathlib import Path
+
+from apify_client import ApifyClient
+
+TOKEN = 'MY-APIFY-TOKEN'
+
+
+def main() -> None:
+    apify_client = ApifyClient(TOKEN)
+    kvs_client = apify_client.key_value_store('MY-KVS-ID')
+
+    screenshot = Path('screenshot.png').read_bytes()
+
+    # The explicit content type lets the client skip compressing the PNG.
+    kvs_client.set_record('screenshot', screenshot, content_type='image/png')

src/apify_client/_consts.py

@@ -34,3 +34,56 @@
 
 OVERRIDABLE_DEFAULT_HEADERS = {'Accept', 'Authorization', 'Accept-Encoding', 'User-Agent'}
 """Headers that can be overridden by users, but will trigger a warning if they do so, as it may lead to API errors."""
+
+ALREADY_COMPRESSED_MEDIA_TYPE_PREFIXES = ('audio/', 'image/', 'video/')
+"""Media type prefixes whose payloads carry their own compression, so compressing the request body is wasted work."""
+
+ALREADY_COMPRESSED_MEDIA_TYPES = frozenset(
+    {
+        'application/epub+zip',
+        'application/gzip',
+        'application/java-archive',
+        'application/vnd.android.package-archive',
+        'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+        'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+        'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+        'application/vnd.rar',
+        'application/x-7z-compressed',
+        'application/x-bzip',
+        'application/x-bzip2',
+        'application/x-gzip',
+        'application/x-rar-compressed',
+        'application/x-xz',
+        'application/x-zip-compressed',
+        'application/zip',
+        'application/zstd',
+        'font/woff',
+        'font/woff2',
+    }
+)
+"""Exact media types whose payloads carry their own compression."""
+
+COMPRESSIBLE_MEDIA_TYPES = frozenset(
+    {
+        'audio/aiff',
+        'audio/basic',
+        'audio/l16',
+        'audio/l24',
+        'audio/midi',
+        'audio/vnd.wave',
+        'audio/wav',
+        'audio/wave',
+        'audio/x-aiff',
+        'audio/x-wav',
+        'image/bmp',
+        'image/tiff',
+        'image/vnd.adobe.photoshop',
+        'image/vnd.microsoft.icon',
+        'image/x-icon',
+        'image/x-ms-bmp',
+    }
+)
+"""Uncompressed media types that sit under an already-compressed prefix, so compressing them still pays off."""
+
+COMPRESSIBLE_MEDIA_TYPE_SUFFIXES = ('+json', '+xml')
+"""Structured syntax suffixes marking a media type as text even under an already-compressed prefix (`image/svg+xml`)."""

src/apify_client/_utils/http.py

@@ -3,7 +3,13 @@
 import warnings
 from typing import TYPE_CHECKING
 
-from apify_client._consts import OVERRIDABLE_DEFAULT_HEADERS
+from apify_client._consts import (
+    ALREADY_COMPRESSED_MEDIA_TYPE_PREFIXES,
+    ALREADY_COMPRESSED_MEDIA_TYPES,
+    COMPRESSIBLE_MEDIA_TYPE_SUFFIXES,
+    COMPRESSIBLE_MEDIA_TYPES,
+    OVERRIDABLE_DEFAULT_HEADERS,
+)
 
 if TYPE_CHECKING:
     from apify_client.http_clients import HttpResponse
@@ -21,6 +27,34 @@ def to_safe_id(id: str) -> str:
     return id.replace('/', '~')
 
 
+def is_compressible_content_type(content_type: str | None) -> bool:
+    """Decide whether a request body with the given content type is worth compressing.
+
+    Images, audio, video and archives already carry their own compression. Running them through gzip or brotli
+    burns CPU, holds a second full copy of the body in memory, and usually produces output slightly larger than
+    the input. Formats that are raw despite such a media type, for example `image/bmp` or `audio/wav`, are still
+    compressed. A body with no content type is assumed to be compressible.
+
+    Args:
+        content_type: The value of the `Content-Type` header, if any.
+
+    Returns:
+        `True` if the body should be compressed before it is sent.
+    """
+    if not content_type:
+        return True
+
+    # `Content-Type` is case-insensitive and may carry parameters, for example `text/plain; charset=utf-8`.
+    media_type = content_type.split(';', 1)[0].strip().lower()
+
+    if media_type in COMPRESSIBLE_MEDIA_TYPES or media_type.endswith(COMPRESSIBLE_MEDIA_TYPE_SUFFIXES):
+        return True
+
+    return not (
+        media_type in ALREADY_COMPRESSED_MEDIA_TYPES or media_type.startswith(ALREADY_COMPRESSED_MEDIA_TYPE_PREFIXES)
+    )
+
+
 def response_to_dict(response: HttpResponse) -> dict:
     """Parse the API response as a dictionary and validate its type.
 

src/apify_client/http_clients/_base.py

@@ -19,6 +19,7 @@
 )
 from apify_client._docs import docs_group
 from apify_client._statistics import ClientStatistics
+from apify_client._utils.http import is_compressible_content_type
 from apify_client._utils.time import to_seconds
 from apify_client.http_compressors._gzip import GzipHttpCompressor
 
@@ -232,29 +233,41 @@ def _prepare_request_call(
     ) -> tuple[dict[str, str], dict[str, Any] | None, bytes | None]:
         """Prepare headers, params, and body for an HTTP request.
 
-        Merges the client's default headers (including authorization) with per-request headers,
-        serializes JSON and compresses the body. Header names are treated case-insensitively and
-        per-request values win over the client defaults. For JSON bodies, a `Content-Type` header
-        is set unless the caller supplied one.
+        Merges the client's default headers (including authorization) with per-request headers, serializes JSON
+        and compresses the body unless its content type says the payload is already compressed. Header names are
+        treated case-insensitively and per-request values win over the client defaults. For JSON bodies, a
+        `Content-Type` header is set unless the caller supplied one. `Content-Encoding` always describes what was
+        actually applied to the body, so a caller-supplied value is dropped whenever nothing was compressed.
         """
         if json is not None and data is not None:
             raise ValueError('Cannot pass both "json" and "data" parameters at the same time!')
 
         headers = self._merge_headers(self._headers, headers)
 
-        # Dump JSON data to string so it can be compressed.
+        # Dump JSON data to a string so it can be sent as a request body.
         if json is not None:
             data = jsonlib.dumps(json, ensure_ascii=False, allow_nan=False, default=str).encode('utf-8')
             if not any(key.lower() == 'content-type' for key in headers):
                 headers['Content-Type'] = 'application/json'
 
+        compressed = False
+
         if isinstance(data, (str, bytes, bytearray)):
             if isinstance(data, str):
                 data = data.encode('utf-8')
             elif isinstance(data, bytearray):
                 data = bytes(data)
-            data = self._http_compressor.compress(data)
-            headers = self._merge_headers(headers, {'Content-Encoding': self._http_compressor.content_encoding})
+
+            content_type = next((value for key, value in headers.items() if key.lower() == 'content-type'), None)
+            if is_compressible_content_type(content_type):
+                data = self._http_compressor.compress(data)
+                headers = self._merge_headers(headers, {'Content-Encoding': self._http_compressor.content_encoding})
+                compressed = True
+
+        # Anything left uncompressed goes out as-is - a file-like body included - so a caller-supplied encoding
+        # would misdescribe it.
+        if data is not None and not compressed:
+            headers = {key: value for key, value in headers.items() if key.lower() != 'content-encoding'}
 
         return (headers, self._parse_params(params), data)
 

src/apify_client/http_clients/_impit.py

@@ -395,8 +395,8 @@ async def call(
         self._statistics.calls += 1
 
         # Serializing and compressing a request body is CPU-bound and would block the event loop, so
-        # offload request preparation to a worker thread whenever there is a body to compress. Bodyless
-        # requests skip the thread hop, as they have no expensive work to move off the loop.
+        # offload request preparation to a worker thread whenever there is a body. Bodyless requests
+        # skip the thread hop, as they have no expensive work to move off the loop.
         if json is not None or data is not None:
             prepared_headers, prepared_params, content = await asyncio.to_thread(
                 self._prepare_request_call,

tests/unit/test_http_clients.py

@@ -2,10 +2,11 @@
 
 import asyncio
 import gzip
+import io
 import threading
 import time
 from datetime import UTC, datetime, timedelta
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 from unittest.mock import AsyncMock, Mock
 
 import brotli
@@ -461,6 +462,83 @@ def test_prepare_request_call_with_bytearray_data(compressor_case: tuple) -> Non
     assert decompress(data) == b'test bytearray'
 
 
+@pytest.mark.parametrize(
+    'content_type',
+    [
+        pytest.param('image/png', id='image'),
+        pytest.param('video/mp4', id='video'),
+        pytest.param('application/zip', id='archive'),
+    ],
+)
+def test_prepare_request_call_skips_compression_for_already_compressed_content(content_type: str) -> None:
+    """An already-compressed body is sent verbatim, carries no `Content-Encoding`, and keeps every other header."""
+    client = _ConcreteHttpClient(token='test_token', http_compressor=GzipHttpCompressor())
+
+    headers, _params, data = client._prepare_request_call(
+        headers={'content-type': content_type},
+        data=b'\x89PNG binary',
+    )
+
+    assert data == b'\x89PNG binary'
+    assert not any(key.lower() == 'content-encoding' for key in headers)
+    assert headers['Authorization'] == 'Bearer test_token'
+    assert headers['content-type'] == content_type
+    assert headers['User-Agent'] == client._headers['User-Agent']
+
+
+def test_prepare_request_call_drops_caller_content_encoding_when_compression_is_skipped() -> None:
+    """Skipping compression also strips a caller-supplied `Content-Encoding`, which would misdescribe the body."""
+    client = _ConcreteHttpClient(http_compressor=GzipHttpCompressor())
+
+    headers, _params, data = client._prepare_request_call(
+        headers={'content-type': 'image/jpeg', 'content-encoding': 'br'},
+        data=b'jpeg binary',
+    )
+
+    assert data == b'jpeg binary'
+    assert not any(key.lower() == 'content-encoding' for key in headers)
+
+
+def test_prepare_request_call_drops_caller_content_encoding_for_a_streamed_body() -> None:
+    """A body that is streamed rather than compressed, such as a file-like object, also loses `Content-Encoding`."""
+    client = _ConcreteHttpClient(http_compressor=GzipHttpCompressor())
+    stream = io.BytesIO(b'raw payload')
+
+    headers, _params, data = client._prepare_request_call(
+        headers={'content-encoding': 'gzip'},
+        data=cast('bytes', stream),
+    )
+
+    assert data is stream
+    assert not any(key.lower() == 'content-encoding' for key in headers)
+
+
+@pytest.mark.parametrize(
+    'content_type',
+    [
+        pytest.param('image/svg+xml', id='structured xml suffix'),
+        pytest.param('image/bmp', id='raw bitmap'),
+        pytest.param('audio/wav', id='raw audio'),
+    ],
+)
+def test_prepare_request_call_compresses_exceptions_to_compressed_prefixes(
+    content_type: str,
+    compressor_case: tuple,
+) -> None:
+    """Types that are text or raw are compressed even when they sit under an already-compressed prefix."""
+    compressor, content_encoding, decompress = compressor_case
+    client = _ConcreteHttpClient(http_compressor=compressor)
+
+    headers, _params, data = client._prepare_request_call(
+        headers={'content-type': content_type},
+        data=b'raw payload',
+    )
+
+    assert headers['Content-Encoding'] == content_encoding
+    assert isinstance(data, bytes)
+    assert decompress(data) == b'raw payload'
+
+
 def test_prepare_request_call_json_and_data_error() -> None:
     """Test _prepare_request_call raises error when both json and data are provided."""
     client = _ConcreteHttpClient()
@@ -520,7 +598,7 @@ def test_prepare_request_call_json_keeps_caller_content_type() -> None:
 
 
 def test_prepare_request_call_replaces_caller_content_encoding() -> None:
-    """The Content-Encoding header always reflects the compressor actually applied, replacing any caller value."""
+    """A compressed body reports the compressor actually applied, replacing any caller-supplied Content-Encoding."""
     client = _ConcreteHttpClient(http_compressor=GzipHttpCompressor())
 
     headers, _params, _data = client._prepare_request_call(headers={'content-encoding': 'br'}, data='payload')