1+ """
2+ Background thread that monitors and kills long-running compilation processes.
3+ Runs as part of the FastAPI application.
4+ """
5+ import os
6+ import time
7+ import signal
8+ import threading
9+ import subprocess
10+ from datetime import datetime
11+
12+ # Configuration
13+ MAX_PROCESS_AGE = 8 # Kill compilation processes older than 8 seconds
14+ CHECK_INTERVAL = 2 # Check every 2 seconds
15+
16+
17+ class ProcessMonitor :
18+ def __init__ (self ):
19+ self .running = False
20+ self .thread = None
21+ self .processes = {} # Track subprocess PIDs we start
22+
23+ def register_process (self , pid ):
24+ """Register a compilation process to monitor"""
25+ self .processes [pid ] = time .time ()
26+ print (f"[MONITOR] Tracking compilation process PID { pid } )
27+
28+ def start (self ):
29+ """Start the monitor thread"""
30+ if not self .running :
31+ self .running = True
32+ self .thread = threading .Thread (target = self ._monitor_loop , daemon = True )
33+ self .thread .start ()
34+ print ("[MONITOR] Process monitor started" )
35+
36+ def stop (self ):
37+ """Stop the monitor thread"""
38+ self .running = False
39+
40+ def _monitor_loop (self ):
41+ """Main monitoring loop that runs in background"""
42+ while self .running :
43+ try :
44+ current_time = time .time ()
45+ pids_to_remove = []
46+
47+ # Check tracked processes
48+ for pid , start_time in list (self .processes .items ()):
49+ age = current_time - start_time
50+
51+ try :
52+ # Check if process still exists
53+ os .kill (pid , 0 ) # Signal 0 just checks if process exists
54+
55+ if age > MAX_PROCESS_AGE :
56+ print (f"[MONITOR] Killing stuck process PID { pid } { age :.1f} )
57+ try :
58+ # Try graceful termination first
59+ os .kill (pid , signal .SIGTERM )
60+ time .sleep (0.5 )
61+ # Check if still alive
62+ os .kill (pid , 0 )
63+ # If still alive, force kill
64+ os .kill (pid , signal .SIGKILL )
65+ print (f"[MONITOR] Force killed PID { pid } )
66+ except OSError :
67+ pass # Process already dead
68+ pids_to_remove .append (pid )
69+
70+ except OSError :
71+ # Process doesn't exist anymore
72+ pids_to_remove .append (pid )
73+
74+ # Clean up dead processes from tracking
75+ for pid in pids_to_remove :
76+ del self .processes [pid ]
77+
78+ # Also check for any zxbc processes we didn't start
79+ # (in case of threading issues)
80+ self ._check_orphan_processes ()
81+
82+ except Exception as e :
83+ print (f"[MONITOR] Error in monitor loop: { e } )
84+
85+ time .sleep (CHECK_INTERVAL )
86+
87+ def _check_orphan_processes (self ):
88+ """Check for compilation processes we might not be tracking"""
89+ try :
90+ # Use ps to find zxbc processes
91+ result = subprocess .run (
92+ ["ps" , "aux" ],
93+ capture_output = True ,
94+ text = True ,
95+ timeout = 1
96+ )
97+
98+ for line in result .stdout .split ('\n ' ):
99+ # The app only ever spawns the zxbc compiler for compilation, so
100+ # match on the executable name rather than specific flags. The
101+ # zxbasic console script appears in ps as ".../bin/zxbc".
102+ if 'zxbc' in line :
103+ parts = line .split ()
104+ if len (parts ) > 1 :
105+ pid = int (parts [1 ])
106+ # If we're not tracking this PID, it might be orphaned
107+ if pid not in self .processes :
108+ # Check process age using /proc if available
109+ try :
110+ stat_path = f"/proc/{ pid }
111+ if os .path .exists (stat_path ):
112+ with open (stat_path , 'r' ) as f :
113+ stat_data = f .read ().split ()
114+ # Field 21 is start time in jiffies
115+ start_jiffies = int (stat_data [21 ])
116+ # Rough age calculation
117+ age_seconds = (time .time () - os .path .getmtime (stat_path ))
118+ if age_seconds > MAX_PROCESS_AGE :
119+ print (f"[MONITOR] Found orphan zxbc process PID { pid } )
120+ os .kill (pid , signal .SIGKILL )
121+ except :
122+ pass
123+ except :
124+ pass # PS might not be available or fail
125+
126+
127+ # Global monitor instance
128+ process_monitor = ProcessMonitor ()
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