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more aggressive, recursive kill on abort

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some jobs may spawn child processes which change their process group
or session id, making the existing abort behavior of HUP-then-KILL to
the process group ineffective. Instead, if HUP to the process group
fails, recursively walk /proc and KILL anything with a ppid corresponding
to the leader process. This should keep working because the leader
process is a subreaper.

resolves #129
This commit is contained in:
Oliver Giles 2020-08-08 12:03:52 +12:00
parent 7f7e8d2455
commit 8a4992e6af
1 changed files with 45 additions and 5 deletions
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50
src/leader.cpp
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@ -20,6 +20,7 @@
#include <string>
#include <unistd.h>
#include <queue>
#include <dirent.h>
#include <sys/prctl.h>
#include <sys/types.h>
#include <sys/wait.h>
@ -45,6 +46,39 @@ struct Script {
bool runOnAbort;
};
static void aggressive_recursive_kill(pid_t parent) {
DIR* proc = opendir("/proc");
if(!proc)
return;
while(struct dirent* de = readdir(proc)) {
if(!isdigit(*de->d_name))
continue;
char status_file[640];
sprintf(status_file, "/proc/%s/status", de->d_name);
FILE* status_fp = fopen(status_file, "rb");
if(!status_fp)
continue;
char status_buffer[512];
int n = fread(status_buffer, 1, 512, status_fp);
if(char* p = (char*)memmem(status_buffer, n, "PPid:\t", 6)) {
pid_t ppid = strtol(p + 6, NULL, 10);
if(ppid == parent) {
pid_t pid = atoi(de->d_name);
aggressive_recursive_kill(pid);
fprintf(stderr, "[laminar] sending SIGKILL to pid %d\n", pid);
kill(pid, SIGKILL);
}
}
fclose(status_fp);
}
closedir(proc);
}
class Leader final : public kj::TaskSet::ErrorHandler {
public:
Leader(kj::AsyncIoContext& ioContext, kj::Filesystem& fs, const char* jobName, uint runNumber);
@ -67,6 +101,7 @@ private:
pid_t currentScriptPid;
std::queue<Script> scripts;
int setEnvPipe[2];
bool aborting;
};
Leader::Leader(kj::AsyncIoContext &ioContext, kj::Filesystem &fs, const char *jobName, uint runNumber) :
@ -76,7 +111,8 @@ Leader::Leader(kj::AsyncIoContext &ioContext, kj::Filesystem &fs, const char *jo
home(fs.getCurrent()),
rootPath(fs.getCurrentPath()),
jobName(jobName),
runNumber(runNumber)
runNumber(runNumber),
aborting(false)
{
tasks.add(ioContext.unixEventPort.onSignal(SIGTERM).then([this](siginfo_t) {
while(scripts.size() && (!scripts.front().runOnAbort))
@ -84,8 +120,8 @@ Leader::Leader(kj::AsyncIoContext &ioContext, kj::Filesystem &fs, const char *jo
// TODO: probably shouldn't do this if we are already in a runOnAbort script
kill(-currentGroupId, SIGTERM);
return this->ioContext.provider->getTimer().afterDelay(2*kj::SECONDS).then([this]{
fprintf(stderr, "[laminar] sending SIGKILL to process group %d\n", currentGroupId);
kill(-currentGroupId, SIGKILL);
aborting = true;
aggressive_recursive_kill(getpid());
});
}));
@ -223,14 +259,18 @@ kj::Promise<void> Leader::reapChildProcesses()
// waiting for is done
return reapChildProcesses();
}
// we were aborted by the primary process already, just wait until all
// SIGKILLs are processed
if(aborting) {
return reapChildProcesses();
}
// Otherwise, reparented orphans are on borrowed time
// TODO list wayward processes?
fprintf(stderr, "[laminar] sending SIGHUP to adopted child processes\n");
kill(-currentGroupId, SIGHUP);
return ioContext.provider->getTimer().afterDelay(5*kj::SECONDS).then([this]{
fprintf(stderr, "[laminar] sending SIGKILL to process group %d\n", currentGroupId);
// TODO: should we mark the job as failed if we had to kill reparented processes?
kill(-currentGroupId, SIGKILL);
aggressive_recursive_kill(getpid());
return reapChildProcesses();
}).exclusiveJoin(reapChildProcesses());
} else if(pid == currentScriptPid) {