[WebConsole] Implement Samply profile collection UI #5423

Karakatiza666 · 2026-01-14T08:59:07Z

I renamed the "Profiler" tab to "Dataflow visualizer" to disambiguate the new functionality.
I also updated API response status code of some Samply responses, added a way to retrieve the estimate for the profile already being collected, and added a way to catch if the profile collection failed immediately by waiting for a set time after the profile was requested

Copilot

Pull request overview

This PR implements a user interface for collecting and downloading Samply CPU profiles in the Feldera web console. The "Profiler" tab has been renamed to "Dataflow Visualizer" to differentiate it from the new Samply profiling functionality.

Changes:

Added new Samply profile collection UI with configurable duration and visual progress indicator
Implemented backend support for tracking in-progress profile collection with expected completion times
Updated API to return status 202 (Accepted) when starting collection and 307 (Temporary Redirect) when profile is in progress
Enhanced error message formatting by preserving newlines in error details

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
openapi.json	Updated API responses: 202 for profile start, 307 for in-progress, changed error details schema to Value
js-packages/web-console/src/lib/services/pipelineManager.ts	Added collectSamplyProfile and getLatestSamplyProfile wrapper functions
js-packages/web-console/src/lib/services/manager/types.gen.ts	Auto-generated type updates from OpenAPI changes
js-packages/web-console/src/lib/compositions/useToastNotification.ts	Added whitespace-pre-wrap to preserve newlines in error messages
js-packages/web-console/src/lib/compositions/usePipelineManager.svelte.ts	Integrated new Samply profile API functions
js-packages/web-console/src/lib/components/pipelines/editor/TabSamplyProfile.svelte	New component implementing profile collection UI with countdown timer and progress visualization
js-packages/web-console/src/lib/components/pipelines/editor/TabProfileVisualizer.svelte	Renamed label to "Dataflow Visualizer"
js-packages/web-console/src/lib/components/pipelines/editor/MonitoringPanel.svelte	Added Samply tab to monitoring panel
js-packages/web-console/src/lib/components/pipelines/editor/InteractionPanel.svelte	Added Samply tab to interaction panel
js-packages/web-console/src/lib/components/pipelines/editor/DownloadSupportBundle.svelte	Removed Oxford comma from tooltip
js-packages/web-console/package.json	Updated build-openapi command to use -p flag
js-packages/web-console/.prettierignore	Added .svelte-kit/ and build/ directories
crates/pipeline-manager/src/api/endpoints/pipeline_interaction.rs	Updated OpenAPI documentation for status codes
crates/feldera-types/src/error.rs	Changed error details schema from Object to Value
crates/adapters/src/server/error.rs	Changed error details schema from Object to Value
crates/adapters/src/server.rs	Implemented InProgress state handling and immediate error detection
crates/adapters/src/samply.rs	Added InProgress variant to SamplyProfile enum
crates/adapters/src/controller.rs	Removed newline escaping in error messages

Copilot · 2026-01-14T09:07:05Z

js-packages/web-console/src/lib/components/pipelines/editor/TabSamplyProfile.svelte

+  let isCollecting = $state(false)
+  let startTime = $state<number | null>(null)
+  let expectedCompletion = $state<number | null>(null)
+  let profileReady = $state(false)


The profileReady state variable is set to true when the countdown completes (line 109) but is never used anywhere in the component. This state variable should either be removed if it's not needed, or used to provide visual feedback to the user that the profile is ready for download.

Suggested change

let profileReady = $state(false)

Copilot · 2026-01-14T09:07:05Z

js-packages/web-console/src/lib/components/pipelines/editor/TabSamplyProfile.svelte

+      if (profile.expectedInSeconds) {
+        // Profile is still being collected, update countdown with the server's expected time
+        const now = Date.now()
+        expectedCompletion = now + profile.expectedInSeconds * 1000
+
+        // Ensure collecting state is active
+        if (!isCollecting) {
+          isCollecting = true
+          profileReady = false
+          startTime = now
+          startCountdown()
+        }


When synchronizing the countdown with the server's expected time in the download handler, the duration variable should also be updated to match the remaining time. Without this, if a user comes back later and clicks download while a profile is being collected, the UI progress bar and time display will be inconsistent because they're calculated based on the duration variable (see lines 44-61), not the actual remaining time from the server.

Copilot · 2026-01-14T09:07:05Z

crates/adapters/src/server.rs


-    Ok(HttpResponse::Ok().finish())
+    // Wait to check if it errored out immediately
+    sleep(Duration::from_millis(600)).await;


The hard-coded 600ms wait time lacks documentation explaining why this specific duration was chosen. Consider adding a comment explaining that this delay allows the system to detect if profiling fails immediately, or extracting this as a named constant with a descriptive name.

Copilot · 2026-01-14T09:07:06Z

js-packages/web-console/src/lib/components/pipelines/editor/TabSamplyProfile.svelte

+</script>
+
+{#snippet label()}
+  <span class=""> CPU Profile </span>


The tab label "CPU Profile" is inconsistent with the tab name "Samply" used in the tab configuration. Consider using a more consistent label such as "Samply Profile" or aligning the tab name with "CPU Profile" to avoid confusion.

Suggested change

<span class=""> CPU Profile </span>

<span class=""> Samply Profile </span>

Copilot · 2026-01-14T09:07:06Z

crates/adapters/src/server.rs

+    // Set the state to InProgress with expected completion time
+    let expected_after = chrono::Utc::now() + chrono::Duration::seconds(duration as i64);
+    *state_samply_profile.lock().unwrap() = SamplyProfile::InProgress { expected_after };
+
    spawn(async move {
        let result = controller.async_samply_profile(duration).await;
        state_samply_profile.lock().unwrap().update(result);
    });


There is no protection against concurrent profile collection requests. If multiple requests to start profiling are made while a profile is already being collected, the state will be overwritten and multiple profiling tasks will run concurrently, competing to update the shared state. Consider adding a check to return an error (e.g., 409 Conflict) if a profile collection is already in progress (when state is InProgress).

mihaibudiu · 2026-01-14T17:30:07Z

"dataflow graph" is a completely static notion, it does not have any relationship with performance.
"performance measurements" is better.
You also have to update the documentation for the profiler if you make UI changes.

ryzhyk · 2026-01-14T19:26:02Z

"dataflow graph" is a completely static notion, it does not have any relationship with performance. "performance measurements" is better. You also have to update the documentation for the profiler if you make UI changes.

I thought "profiler" was perfect? What are we trying to disambiguate?

lalithsuresh · 2026-01-14T19:36:52Z

I agree with @ryzhyk . "Profiler" was perfect.

gz · 2026-01-21T01:23:19Z

please work with abhinav so this is an advertised feature in /v0/config and the tab is not displayed if the feature is not enabled in the backend

crates/adapters/src/controller.rs

abhizer · 2026-01-23T20:03:02Z

crates/adapters/src/samply.rs

+pub(crate) type SamplyProfile = Option<Result<Vec<u8>, String>>;
+
+// Minimal perf_event_attr structure for capability checking
+// We only need the fields that are used in the check
+#[repr(C)]
+struct PerfEventAttr {
+    type_: u32,
+    size: u32,
+    config: u64,
+    // The rest of the struct is zeroed, which is fine for our minimal check
+    _padding: [u8; 112], // perf_event_attr is 136 bytes total, we've used 16
+}
+
+// perf_event_open constants
+const PERF_TYPE_SOFTWARE: u32 = 1;
+const PERF_COUNT_SW_CPU_CLOCK: u64 = 0;
+
+/// Check if profiling is available by attempting a minimal perf_event_open syscall.
+///
+/// Returns `Ok(())` if profiling is available, or `Err(reason)` if not.
+/// This is a low-overhead check that doesn't actually start any profiling.
+pub(crate) fn check_profiling_available() -> Result<(), String> {
+    // Use perf_event_open to check if we have the necessary permissions.
+    // We use a minimal configuration that should succeed if we have PERFMON capability.
+    unsafe {
+        // Initialize perf_event_attr structure with zeros
+        let mut attr: PerfEventAttr = std::mem::zeroed();
+        attr.type_ = PERF_TYPE_SOFTWARE;
+        attr.size = std::mem::size_of::<PerfEventAttr>() as u32;
+        attr.config = PERF_COUNT_SW_CPU_CLOCK;
+
+        // Try to open a perf event for the current process on any CPU
+        // pid=0 means current process, cpu=-1 means any CPU
+        let fd = libc::syscall(
+            libc::SYS_perf_event_open,
+            &attr as *const PerfEventAttr,
+            0i32,  // pid: current process
+            -1i32, // cpu: any CPU
+            -1i32, // group_fd: no group
+            0u64,  // flags: none
+        );
+
+        if fd < 0 {
+            let errno = *libc::__errno_location();
+            let error = std::io::Error::from_raw_os_error(errno);
+
+            // Check for permission-related errors
+            if error.kind() == ErrorKind::PermissionDenied
+                || errno == libc::EACCES
+                || errno == libc::EPERM
+            {
+                return Err(format!(
+                    "CPU profiling is not enabled. In Kubernetes environments, ensure the Helm flag `pipeline.allowProfiling` is set to true. ({})",
+                    error
+                ));
+            }
+            // Other errors might be transient or unrelated to permissions
+            return Err(format!("perf_event_open failed: {}", error));
+        }
+
+        // Successfully opened - close the file descriptor
+        libc::close(fd as i32);
+    }
+
+    Ok(())
+}


At this point, it might just be simpler to just invoke samply profiling once for a second, and see if it gives an error.

That's the plan, it looks like all other methods need tuning. I plan to do this check in a different PR to get this one out. Without it the user will just see an error popup when profiling is not enabled and they try to collect one.

crates/pipeline-manager/src/api/endpoints/pipeline_interaction.rs

abhizer · 2026-01-24T12:17:55Z

crates/adapters/src/server.rs

+
+    // Check if profiling is still running or failed immediately
+    let samply_state = state.samply_state.lock().unwrap();
+    Ok(match samply_state.samply_status {
+        // Profile is still running - return success
+        SamplyStatus::InProgress { .. } => HttpResponse::Accepted().finish(),
+        // Profile completed during wait - check if it failed
+        SamplyStatus::Idle => match &samply_state.last_profile {
+            Some(Err(error)) => samply_profile_error_response(error),
+            _ => HttpResponse::InternalServerError().json(ErrorResponse {
+                message: "samply profiling completed unexpectedly".to_string(),
+                error_code: "SamplyProfilingUnexpectedCompletion".into(),
+                details: serde_json::Value::Null,
+            }),
+        },
+    })


I am not sure if waiting and checking the status this way is ideal. This api is meant to be async.
This api, should:

trigger a profiling session

or, report that it is already in progress

Then, if an error occurs when profiling, the onus is on the client to call the GET api and check for success / failure.

The problem I encountered was when initiating a profile on a misconfigured system I got an HTTP 202 Accepted response, but Samply refused to run immediately due to system profiling permissions. I believe this needs to be seen immediately, even at a cost of <1 s delay - otherwise you need to introduce polling for the status of Samply which is an unnecessary complexity. Now you just make sure that the profile collection has started, and you know how long to wait for the result.
The API is still conceptually async, but it handles a startup failure.

abhizer

Went through only the Rust parts

Signed-off-by: Karakatiza666 <[email protected]>

Hide 'Download profile' button until one is available Signed-off-by: Karakatiza666 <[email protected]>

…because it does not work as expected Signed-off-by: Karakatiza666 <[email protected]>

Signed-off-by: Karakatiza666 <[email protected]>

Signed-off-by: feldera-bot <[email protected]>

Karakatiza666 requested review from abhizer, Copilot and mihaibudiu January 14, 2026 08:59

Copilot started reviewing on behalf of Karakatiza666 January 14, 2026 08:59 View session

Karakatiza666 force-pushed the samply-ui branch from 9a32617 to 06565a8 Compare January 14, 2026 09:04

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Karakatiza666 marked this pull request as draft January 14, 2026 14:52

Karakatiza666 force-pushed the samply-ui branch from 27c3c4c to 4527d3c Compare January 16, 2026 17:19

gz added the marketing Relevant for marketing content label Jan 20, 2026

Karakatiza666 force-pushed the samply-ui branch from 45d39a2 to 7cff437 Compare January 20, 2026 22:35

Karakatiza666 force-pushed the samply-ui branch from 7cff437 to 594182a Compare January 23, 2026 10:01

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Karakatiza666 marked this pull request as ready for review January 23, 2026 23:09

abhizer reviewed Jan 24, 2026

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Karakatiza666 force-pushed the samply-ui branch from 4b46129 to 771d9ec Compare January 25, 2026 17:06

Karakatiza666 enabled auto-merge January 25, 2026 17:06

Karakatiza666 force-pushed the samply-ui branch from f994856 to 708e5a0 Compare January 26, 2026 06:54

abhizer approved these changes Jan 26, 2026

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Karakatiza666 added 3 commits January 26, 2026 15:48

[WebConsole] Implement Samply profile collection UI

ccaf1f5

Signed-off-by: Karakatiza666 <[email protected]>

[WebConsole] Add a warning when Samply profiling is not available

3aac48a

Hide 'Download profile' button until one is available Signed-off-by: Karakatiza666 <[email protected]>

[dbsp_adapters] Temporarily remove a check that profiling is enabled …

4668baf

…because it does not work as expected Signed-off-by: Karakatiza666 <[email protected]>

[dbsp_adapters] Fix openapi generation

782b758

Signed-off-by: Karakatiza666 <[email protected]>

Karakatiza666 force-pushed the samply-ui branch from 0f561cb to 782b758 Compare January 26, 2026 15:48

[ci] apply automatic fixes

f6a125b

Signed-off-by: feldera-bot <[email protected]>

Karakatiza666 added this pull request to the merge queue Jan 26, 2026

Merged via the queue into main with commit d3e2788 Jan 26, 2026
1 check passed

Karakatiza666 deleted the samply-ui branch January 26, 2026 17:10

	<span class=""> CPU Profile </span>
	<span class=""> Samply Profile </span>

[WebConsole] Implement Samply profile collection UI #5423

[WebConsole] Implement Samply profile collection UI #5423

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