Open
Description
See #7526 for context.
When running in gVisor, /proc/stat is all zeros and we don't set CpuUsage, which has the side-effect of disabling Cpu-based loadshedding.
We should fall back to /proc/self/stat before failing.
Example app running in gVisor
Legend per https://man7.org/linux/man-pages/man5/proc.5.html:
/proc/[pid]/stat
Status information about the process. This is used by
[ps(1)](https://man7.org/linux/man-pages/man1/ps.1.html). It is defined in the kernel source file
fs/proc/array.c.
The fields, in order, with their proper [scanf(3)](https://man7.org/linux/man-pages/man3/scanf.3.html) format
specifiers, are listed below. Whether or not certain of
these fields display valid information is governed by a
ptrace access mode PTRACE_MODE_READ_FSCREDS |
PTRACE_MODE_NOAUDIT check (refer to [ptrace(2)](https://man7.org/linux/man-pages/man2/ptrace.2.html)). If the
check denies access, then the field value is displayed as
0. The affected fields are indicated with the marking
[PT].
(1) pid %d
The process ID.
(2) comm %s
The filename of the executable, in parentheses.
Strings longer than TASK_COMM_LEN (16) characters
(including the terminating null byte) are silently
truncated. This is visible whether or not the
executable is swapped out.
(3) state %c
One of the following characters, indicating process
state:
R Running
S Sleeping in an interruptible wait
D Waiting in uninterruptible disk sleep
Z Zombie
T Stopped (on a signal) or (before Linux 2.6.33)
trace stopped
t Tracing stop (Linux 2.6.33 onward)
W Paging (only before Linux 2.6.0)
X Dead (from Linux 2.6.0 onward)
x Dead (Linux 2.6.33 to 3.13 only)
K Wakekill (Linux 2.6.33 to 3.13 only)
W Waking (Linux 2.6.33 to 3.13 only)
P Parked (Linux 3.9 to 3.13 only)
(4) ppid %d
The PID of the parent of this process.
(5) pgrp %d
The process group ID of the process.
(6) session %d
The session ID of the process.
(7) tty_nr %d
The controlling terminal of the process. (The
minor device number is contained in the combination
of bits 31 to 20 and 7 to 0; the major device
number is in bits 15 to 8.)
(8) tpgid %d
The ID of the foreground process group of the
controlling terminal of the process.
(9) flags %u
The kernel flags word of the process. For bit
meanings, see the PF_* defines in the Linux kernel
source file include/linux/sched.h. Details depend
on the kernel version.
The format for this field was %lu before Linux 2.6.
(10) minflt %lu
The number of minor faults the process has made
which have not required loading a memory page from
disk.
(11) cminflt %lu
The number of minor faults that the process's
waited-for children have made.
(12) majflt %lu
The number of major faults the process has made
which have required loading a memory page from
disk.
(13) cmajflt %lu
The number of major faults that the process's
waited-for children have made.
(14) utime %lu
Amount of time that this process has been scheduled
in user mode, measured in clock ticks (divide by
sysconf(_SC_CLK_TCK)). This includes guest time,
guest_time (time spent running a virtual CPU, see
below), so that applications that are not aware of
the guest time field do not lose that time from
their calculations.
(15) stime %lu
Amount of time that this process has been scheduled
in kernel mode, measured in clock ticks (divide by
sysconf(_SC_CLK_TCK)).
(16) cutime %ld
Amount of time that this process's waited-for
children have been scheduled in user mode, measured
in clock ticks (divide by sysconf(_SC_CLK_TCK)).
(See also [times(2)](https://man7.org/linux/man-pages/man2/times.2.html).) This includes guest time,
cguest_time (time spent running a virtual CPU, see
below).
(17) cstime %ld
Amount of time that this process's waited-for
children have been scheduled in kernel mode,
measured in clock ticks (divide by
sysconf(_SC_CLK_TCK)).
(18) priority %ld
(Explanation for Linux 2.6) For processes running a
real-time scheduling policy (policy below; see
[sched_setscheduler(2)](https://man7.org/linux/man-pages/man2/sched_setscheduler.2.html)), this is the negated
scheduling priority, minus one; that is, a number
in the range -2 to -100, corresponding to real-time
priorities 1 to 99. For processes running under a
non-real-time scheduling policy, this is the raw
nice value ([setpriority(2)](https://man7.org/linux/man-pages/man2/setpriority.2.html)) as represented in the
kernel. The kernel stores nice values as numbers
in the range 0 (high) to 39 (low), corresponding to
the user-visible nice range of -20 to 19.
Before Linux 2.6, this was a scaled value based on
the scheduler weighting given to this process.
(19) nice %ld
The nice value (see [setpriority(2)](https://man7.org/linux/man-pages/man2/setpriority.2.html)), a value in the
range 19 (low priority) to -20 (high priority).
(20) num_threads %ld
Number of threads in this process (since Linux
2.6). Before kernel 2.6, this field was hard coded
to 0 as a placeholder for an earlier removed field.
(21) itrealvalue %ld
The time in jiffies before the next SIGALRM is sent
to the process due to an interval timer. Since
kernel 2.6.17, this field is no longer maintained,
and is hard coded as 0.
(22) starttime %llu
The time the process started after system boot. In
kernels before Linux 2.6, this value was expressed
in jiffies. Since Linux 2.6, the value is
expressed in clock ticks (divide by
sysconf(_SC_CLK_TCK)).
The format for this field was %lu before Linux 2.6.
(23) vsize %lu
Virtual memory size in bytes.
(24) rss %ld
Resident Set Size: number of pages the process has
in real memory. This is just the pages which count
toward text, data, or stack space. This does not
include pages which have not been demand-loaded in,
or which are swapped out. This value is
inaccurate; see /proc/[pid]/statm below.
(25) rsslim %lu
Current soft limit in bytes on the rss of the
process; see the description of RLIMIT_RSS in
[getrlimit(2)](https://man7.org/linux/man-pages/man2/getrlimit.2.html).
(26) startcode %lu [PT]
The address above which program text can run.
(27) endcode %lu [PT]
The address below which program text can run.
(28) startstack %lu [PT]
The address of the start (i.e., bottom) of the
stack.
(29) kstkesp %lu [PT]
The current value of ESP (stack pointer), as found
in the kernel stack page for the process.
(30) kstkeip %lu [PT]
The current EIP (instruction pointer).
(31) signal %lu
The bitmap of pending signals, displayed as a
decimal number. Obsolete, because it does not
provide information on real-time signals; use
/proc/[pid]/status instead.
(32) blocked %lu
The bitmap of blocked signals, displayed as a
decimal number. Obsolete, because it does not
provide information on real-time signals; use
/proc/[pid]/status instead.
(33) sigignore %lu
The bitmap of ignored signals, displayed as a
decimal number. Obsolete, because it does not
provide information on real-time signals; use
/proc/[pid]/status instead.
(34) sigcatch %lu
The bitmap of caught signals, displayed as a
decimal number. Obsolete, because it does not
provide information on real-time signals; use
/proc/[pid]/status instead.
(35) wchan %lu [PT]
This is the "channel" in which the process is
waiting. It is the address of a location in the
kernel where the process is sleeping. The
corresponding symbolic name can be found in
/proc/[pid]/wchan.
(36) nswap %lu
Number of pages swapped (not maintained).
(37) cnswap %lu
Cumulative nswap for child processes (not
maintained).
(38) exit_signal %d (since Linux 2.1.22)
Signal to be sent to parent when we die.
(39) processor %d (since Linux 2.2.8)
CPU number last executed on.
(40) rt_priority %u (since Linux 2.5.19)
Real-time scheduling priority, a number in the
range 1 to 99 for processes scheduled under a real-
time policy, or 0, for non-real-time processes (see
[sched_setscheduler(2)](https://man7.org/linux/man-pages/man2/sched_setscheduler.2.html)).
(41) policy %u (since Linux 2.5.19)
Scheduling policy (see [sched_setscheduler(2)](https://man7.org/linux/man-pages/man2/sched_setscheduler.2.html)).
Decode using the SCHED_* constants in
linux/sched.h.
The format for this field was %lu before Linux
2.6.22.
(42) delayacct_blkio_ticks %llu (since Linux 2.6.18)
Aggregated block I/O delays, measured in clock
ticks (centiseconds).
(43) guest_time %lu (since Linux 2.6.24)
Guest time of the process (time spent running a
virtual CPU for a guest operating system), measured
in clock ticks (divide by sysconf(_SC_CLK_TCK)).
(44) cguest_time %ld (since Linux 2.6.24)
Guest time of the process's children, measured in
clock ticks (divide by sysconf(_SC_CLK_TCK)).
(45) start_data %lu (since Linux 3.3) [PT]
Address above which program initialized and
uninitialized (BSS) data are placed.
(46) end_data %lu (since Linux 3.3) [PT]
Address below which program initialized and
uninitialized (BSS) data are placed.
(47) start_brk %lu (since Linux 3.3) [PT]
Address above which program heap can be expanded
with [brk(2)](https://man7.org/linux/man-pages/man2/brk.2.html).
(48) arg_start %lu (since Linux 3.5) [PT]
Address above which program command-line arguments
(argv) are placed.
(49) arg_end %lu (since Linux 3.5) [PT]
Address below program command-line arguments (argv)
are placed.
(50) env_start %lu (since Linux 3.5) [PT]
Address above which program environment is placed.
(51) env_end %lu (since Linux 3.5) [PT]
Address below which program environment is placed.
(52) exit_code %d (since Linux 3.5) [PT]
The thread's exit status in the form reported by
[waitpid(2)](https://man7.org/linux/man-pages/man2/waitpid.2.html).