Save job pid to the database and sing sigint to kill it when stopping so it stops immediatly.

ui/cron/actions/startJob.ts

@@ -125,18 +125,25 @@ const startAndWatchJob = (job: Job) => {
         });
       }
 
+      // Save the PID to the database and a file for future management (stop/inspect)
+      const pid = subprocess.pid ?? null;
+      if (pid != null) {
+        await prisma.job.update({
+          where: { id: jobID },
+          data: { pid },
+        });
+      }
+      try {
+        fs.writeFileSync(path.join(trainingFolder, 'pid.txt'), String(pid ?? ''), { flag: 'w' });
+      } catch (e) {
+        console.error('Error writing pid file:', e);
+      }
+
       // Important: let the child run independently of this Node process.
       if (subprocess.unref) {
         subprocess.unref();
       }
 
-      // Optionally write a pid file for future management (stop/inspect) without keeping streams open
-      try {
-        fs.writeFileSync(path.join(trainingFolder, 'pid.txt'), String(subprocess.pid ?? ''), { flag: 'w' });
-      } catch (e) {
-        console.error('Error writing pid file:', e);
-      }
-
       // (No stdout/stderr listeners — logging should go to --log handled by your Python)
       // (No monitoring loop — the whole point is to let it live past this worker)
     } catch (error: any) {

ui/prisma/schema.prisma

@@ -35,6 +35,7 @@ model Job {
   info            String   @default("")
   speed_string    String   @default("")
   queue_position  Int      @default(0)
+  pid             Int?
 
   @@index([status])
   @@index([gpu_ids])

ui/src/app/api/jobs/[jobID]/mark_stopped/route.ts

@@ -17,6 +17,7 @@ export async function GET(request: NextRequest, { params }: { params: { jobID: s
       stop: true,
       status: 'stopped',
       info: 'Job stopped',
+      pid: null,
     },
   });
 

ui/src/app/api/jobs/[jobID]/stop/route.ts

@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from 'next/server';
 import { PrismaClient } from '@prisma/client';
 
 const prisma = new PrismaClient();
+const isWindows = process.platform === 'win32';
 
 export async function GET(request: NextRequest, { params }: { params: { jobID: string } }) {
   const { jobID } = await params;
@@ -10,7 +11,10 @@ export async function GET(request: NextRequest, { params }: { params: { jobID: s
     where: { id: jobID },
   });
 
-  // update job status to 'running'
+  if (!job) {
+    return NextResponse.json({ error: 'Job not found' }, { status: 404 });
+  }
+
   await prisma.job.update({
     where: { id: jobID },
     data: {
@@ -19,5 +23,33 @@ export async function GET(request: NextRequest, { params }: { params: { jobID: s
     },
   });
 
+  // Send SIGINT to the process if we have a PID
+  if (job.pid != null) {
+    console.log(`Attempting to stop job ${jobID} with PID ${job.pid}`);
+    try {
+      if (isWindows) {
+        // Windows doesn't support SIGINT for arbitrary processes.
+        // Use taskkill with /T (tree) to send a CTRL+C-like termination.
+        const { execSync } = require('child_process');
+        execSync(`taskkill /PID ${job.pid} /T /F`, { stdio: 'ignore' });
+      } else {
+        process.kill(job.pid, 'SIGINT');
+      }
+      // if it killed it, mark it stopped in the database
+      await prisma.job.update({
+        where: { id: jobID },
+        data: {
+          status: 'stopped',
+          info: 'Job stopped',
+        },
+      });
+    } catch (e) {
+      // Process may have already exited — that's fine
+      console.error('Error sending signal to process:', e);
+    }
+  } else {
+    console.warn(`No PID found for job ${jobID}, cannot send stop signal`);
+  }
+
   return NextResponse.json(job);
 }