[browser] native - no process, no signals, no threads, no blocking by pavelsavara · Pull Request #123962 · dotnet/runtime

pavelsavara · 2026-02-03T20:38:00Z

Contributes to #122506

dotnet-policy-service · 2026-02-03T20:39:04Z

Tagging subscribers to this area: @karelz, @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request adds support for the browser (WASM) target by providing stub implementations for features not available in the browser environment, specifically: no sockets, no threads, and no blocking operations.

Changes:

Added browser-specific stub implementations for networking, interface addresses, network statistics, and console APIs
Updated error messages in WASM-specific files from "WASI" to "WASM" for clarity
Modified CoreCLR PAL to prevent blocking operations and thread suspension in single-threaded WASM
Updated build configuration to disable socket support for browser targets and include browser-specific source files
Added perftracing configuration for browser builds

Reviewed changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/native/libs/System.Native/pal_signal_wasm.c	Updated error messages from "WASI" to "WASM"
src/native/libs/System.Native/pal_networkstatistics_wasm.c	New file with stub implementations returning "not supported" for network statistics APIs
src/native/libs/System.Native/pal_networking_browser.c	New file with comprehensive stub implementations for all networking APIs, returning ENOTSUP
src/native/libs/System.Native/pal_io.c	Added early return for pipe() on WASM targets with ENOTSUP
src/native/libs/System.Native/pal_interfaceaddresses_browser.c	New file with stub implementations for interface enumeration APIs
src/native/libs/System.Native/pal_dynamicload_wasm.c	Updated error messages from "WASI" to "WASM"
src/native/libs/System.Native/pal_console_wasm.c	New console implementation for WASM with some working features (stdin/isatty) and stubs for unsupported features
src/native/libs/System.Native/CMakeLists.txt	Updated build configuration to differentiate between browser and WASI targets, using browser-specific source files
src/native/eventpipe/ds-ipc-pal-websocket.c	Added string duplication helper functions for eventpipe
src/mono/mono/profiler/log.c	Changed sys/socket.h include guard from HOST_WIN32 to HAVE_SYS_SOCKET_H
src/mono/mono/profiler/helper.c	Changed sys/socket.h include guard from HOST_WIN32 to HAVE_SYS_SOCKET_H
src/mono/mono/profiler/CMakeLists.txt	Disabled AOT profiler for browser targets
src/mono/mono/mini/cfgdump.c	Added guard for sys/socket.h include
src/mono/browser/runtime/dotnet.d.ts	Formatting fix: removed space before parentheses in function signatures
src/coreclr/pal/src/thread/threadsusp.cpp	Added guard to prevent thread suspension in single-threaded WASM
src/coreclr/pal/src/thread/thread.cpp	Added guard to prevent CREATE_SUSPENDED flag in single-threaded WASM
src/coreclr/pal/src/synchmgr/wait.cpp	Added guards to prevent blocking waits and made Sleep return immediately in WASM
src/coreclr/pal/src/synchmgr/synchmanager.cpp	Added assertion to prevent waiting on non-signaled objects in WASM
src/coreclr/pal/src/debug/debug.cpp	Added WASM-specific implementation of PAL_ProbeMemory using emscripten heap size
eng/native/tryrun.browser.cmake	Disabled HAVE_SYS_SOCKET_H for browser targets
eng/native.wasm.targets	Added perftracing configuration flags for browser builds

src/coreclr/pal/src/debug/debug.cpp

src/native/libs/System.Native/pal_console_wasm.c

src/mono/mono/mini/cfgdump.c

src/coreclr/pal/src/debug/debug.cpp

src/coreclr/pal/src/thread/thread.cpp

src/coreclr/pal/src/synchmgr/synchmanager.cpp

src/coreclr/pal/src/debug/debug.cpp

pavelsavara · 2026-02-04T00:10:11Z

Whole this PR makes emscripten emulator smaller only by 20KB of JavaScript - from 154KB to 134KB.
And only 4KB of .wasm with -O3. Those are CoreCLR numbers, it will have similar impact for Mono but I have not measured it yet.

I hoped for more, I'm not sure I want to merge this...

pavelsavara · 2026-02-04T00:47:28Z

These are JS emulators of mmap that are slow and terrible, we should not use them in CoreCLR

adding _mmap_js (referenced by root reference (e.g. compiled C/C++ code))
adding _msync_js (referenced by root reference (e.g. compiled C/C++ code))
adding _munmap_js (referenced by root reference (e.g. compiled C/C++ code))

The rest of the JS support is OK. See https://gist.github.com/pavelsavara/f11dd1078548a16fc923de444f1c9d9b

All the symbols in the wasm files are https://gist.github.com/pavelsavara/b7653066a83554168739558630d34847

Among them these caught my eye

GetNativeSwiftPhysicalLowering

GetThreadStaticsByIndex
SwitchStackAndExecuteHandler
Thread::HandleThreadAbort
ThreadNative_Abort
ThreadNative_ResetAbort
ThreadNative_Start
ThreadSuspend::LockThreadStore

WKS::gc_heap and SVR::gc_heap

COMDouble
COMSingle
COMDelegate
OleVariant
RealCOMPlusThrow

jkotas · 2026-02-04T00:57:04Z

These are JS emulators of mmap that are slow and terrible, we should not use them in CoreCLR

#117813 is the main offender.

Copilot

Pull request overview

Copilot reviewed 26 out of 27 changed files in this pull request and generated 7 comments.

src/native/libs/System.Native/pal_console_wasm.c

src/mono/mono/mini/cfgdump.c

src/native/libs/System.Native/pal_networking_browser.c

src/mono/sample/wasm/browser/native.sh

src/coreclr/pal/src/debug/debug.cpp

Copilot

Pull request overview

Copilot reviewed 25 out of 26 changed files in this pull request and generated 4 comments.

src/native/libs/System.Native/pal_networking_browser.c

src/mono/sample/wasm/browser/native.sh

src/mono/sample/wasm/browser/linkLibs.rrsp

src/mono/sample/wasm/browser/core-emcc-link.rrsp

Copilot

Pull request overview

Copilot reviewed 27 out of 28 changed files in this pull request and generated 6 comments.

src/native/libs/System.Native/pal_networking_browser.c

src/native/libs/System.Native/pal_networkstatistics_wasm.c

src/native/libs/System.Native/pal_interfaceaddresses_browser.c

Copilot

Pull request overview

Copilot reviewed 24 out of 25 changed files in this pull request and generated 5 comments.

src/native/libs/System.Native/pal_networking_browser.c

src/native/eventpipe/ds-ipc-pal-websocket.c

src/coreclr/pal/src/synchmgr/synchmanager.cpp

src/native/libs/System.Native/pal_networking_browser.c

Copilot

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

Copilot

Pull request overview

Copilot reviewed 15 out of 16 changed files in this pull request and generated 2 comments.

src/native/libs/System.Native/pal_io.c

src/coreclr/pal/src/debug/debug.cpp

src/native/libs/System.Native/pal_console_wasm.c

Copilot

Pull request overview

Copilot reviewed 14 out of 15 changed files in this pull request and generated 3 comments.

src/coreclr/pal/src/synchmgr/wait.cpp

src/coreclr/pal/src/debug/debug.cpp

src/native/eventpipe/ds-ipc-pal-websocket.c

noahfalk

I hoped for more, I'm not sure I want to merge this...

Is there anything you were particularly concerned about? Most of the changes looked like we are just making it clearer what is supported. Those aspects seemed benign and help raise visibility about the platform constraints even if they had no size benefits.

I didn't review everything, but to the degree this intersected the diagnostics stuff it seemed fine to me.

pavelsavara · 2026-02-13T11:28:48Z

I hoped for more, I'm not sure I want to merge this...

I hoped that there will be larger reduction in size of the native binary. And I was not sure about the added code complexity.

The 20KB of JavaScript is good win (with the sockets part I split to separate PR), because that file is on critical path during startup.

pavelsavara · 2026-02-13T15:42:02Z

/ba-g failed CI is infra

…otnet#123962)

pavelsavara added this to the 11.0.0 milestone Feb 3, 2026

pavelsavara self-assigned this Feb 3, 2026

pavelsavara added arch-wasm WebAssembly architecture area-System.Net.Sockets os-browser Browser variant of arch-wasm labels Feb 3, 2026

Copilot AI review requested due to automatic review settings February 3, 2026 20:38

Copilot started reviewing on behalf of pavelsavara February 3, 2026 20:38 View session

Copilot AI reviewed Feb 3, 2026

View reviewed changes

jkotas reviewed Feb 3, 2026

View reviewed changes

src/coreclr/pal/src/thread/thread.cpp Outdated Show resolved Hide resolved

jkotas reviewed Feb 3, 2026

View reviewed changes

src/coreclr/pal/src/synchmgr/synchmanager.cpp Outdated Show resolved Hide resolved

jkotas reviewed Feb 3, 2026

View reviewed changes

src/coreclr/pal/src/debug/debug.cpp Show resolved Hide resolved

Copilot AI review requested due to automatic review settings February 4, 2026 16:42

Copilot started reviewing on behalf of pavelsavara February 4, 2026 16:43 View session

Copilot AI reviewed Feb 4, 2026

View reviewed changes

build-analysis bot mentioned this pull request Feb 5, 2026

Android System.Security.Cryptography test failure: Signing key verifies the CRL #119023

Open

Copilot AI review requested due to automatic review settings February 5, 2026 13:35

Copilot started reviewing on behalf of pavelsavara February 5, 2026 13:36 View session

Copilot AI reviewed Feb 5, 2026

View reviewed changes

Copilot AI review requested due to automatic review settings February 6, 2026 12:27

Copilot started reviewing on behalf of pavelsavara February 6, 2026 12:28 View session

Copilot AI reviewed Feb 6, 2026

View reviewed changes

Copilot AI review requested due to automatic review settings February 6, 2026 14:02

Copilot started reviewing on behalf of pavelsavara February 6, 2026 14:03 View session

Copilot AI reviewed Feb 11, 2026

View reviewed changes

Copilot AI review requested due to automatic review settings February 11, 2026 18:52

Copilot started reviewing on behalf of pavelsavara February 11, 2026 18:53 View session

Copilot AI reviewed Feb 11, 2026

View reviewed changes

build-analysis bot mentioned this pull request Feb 12, 2026

System.Security.Cryptography.CryptographicException : m_safeCertContext is an invalid handle. #124279

Closed

Copilot AI review requested due to automatic review settings February 12, 2026 14:12

Copilot started reviewing on behalf of pavelsavara February 12, 2026 14:13 View session

pavelsavara changed the title ~~[browser] native - no sockets, no threads, no blocking~~ [browser] native - no process, no signals, no threads, no blocking Feb 12, 2026

Copilot AI reviewed Feb 12, 2026

View reviewed changes

src/native/libs/System.Native/pal_io.c Show resolved Hide resolved

src/coreclr/pal/src/debug/debug.cpp Show resolved Hide resolved

pavelsavara added a commit to pavelsavara/runtime that referenced this pull request Feb 12, 2026

move from dotnet#123962

10a13cc

pavelsavara mentioned this pull request Feb 12, 2026

[browser] no sockets #124347

Open

pavelsavara added area-PAL-coreclr and removed area-System.Net.Sockets labels Feb 12, 2026

pavelsavara requested a review from jkotas February 12, 2026 21:31

jkotas reviewed Feb 13, 2026

View reviewed changes

src/native/libs/System.Native/pal_console_wasm.c Show resolved Hide resolved

jkotas requested a review from radekdoulik February 13, 2026 04:10

Copilot AI review requested due to automatic review settings February 13, 2026 07:43

Copilot started reviewing on behalf of pavelsavara February 13, 2026 07:44 View session

rebase, fix console

9ad87e2

pavelsavara force-pushed the browser_no_sockets branch from 4524608 to 9ad87e2 Compare February 13, 2026 07:48

wasm

15243aa

Copilot AI reviewed Feb 13, 2026

View reviewed changes

src/coreclr/pal/src/synchmgr/wait.cpp Show resolved Hide resolved

src/coreclr/pal/src/debug/debug.cpp Show resolved Hide resolved

src/native/eventpipe/ds-ipc-pal-websocket.c Show resolved Hide resolved

noahfalk approved these changes Feb 13, 2026

View reviewed changes

jkotas approved these changes Feb 13, 2026

View reviewed changes

pavelsavara merged commit fdaebbf into dotnet:main Feb 13, 2026
166 of 169 checks passed

pavelsavara deleted the browser_no_sockets branch February 13, 2026 15:42

dotnet-maestro bot mentioned this pull request Feb 14, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#4873

Open

richlander pushed a commit to richlander/runtime that referenced this pull request Feb 14, 2026

[browser] native - no process, no signals, no threads, no blocking (d…

1c3e6b1

…otnet#123962)

Conversation

pavelsavara commented Feb 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

dotnet-policy-service bot commented Feb 3, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

pavelsavara commented Feb 4, 2026

Uh oh!

pavelsavara commented Feb 4, 2026

Uh oh!

jkotas commented Feb 4, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

pavelsavara commented Feb 3, 2026 •

edited

Loading

pavelsavara commented Feb 13, 2026 •

edited

Loading