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Make disowned pid reaping thread-safe

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ridiculousfish 2019-05-22 17:10:33 -07:00
parent 4d929720ce
commit 84febe8f2e
1 changed files with 15 additions and 9 deletions
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24
src/proc.cpp
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@ -292,7 +292,7 @@ typedef unsigned int process_generation_count_t;
/// A list of pids/pgids that have been disowned. They are kept around until either they exit or
/// we exit. Poll these from time-to-time to prevent zombie processes from happening (#5342).
static std::vector<pid_t> s_disowned_pids;
static owning_lock<std::vector<pid_t>> s_disowned_pids;
void add_disowned_pgid(pid_t pgid) {
// NEVER add our own (or an invalid) pgid as they are not unique to only
@ -300,10 +300,21 @@ void add_disowned_pgid(pid_t pgid) {
if (pgid != getpgrp() && pgid > 0) {
// waitpid(2) is signalled to wait on a process group rather than a
// process id by using the negative of its value.
s_disowned_pids.push_back(pgid * -1);
s_disowned_pids.acquire()->push_back(pgid * -1);
}
}
// Reap any pids in our disowned list that have exited. This is used to avoid zombies.
static void reap_disowned_pids() {
auto disowned_pids = s_disowned_pids.acquire();
auto try_reap1 = [](pid_t pid) {
int status;
return waitpid(pid, &status, WNOHANG) > 0;
};
disowned_pids->erase(std::remove_if(disowned_pids->begin(), disowned_pids->end(), try_reap1),
disowned_pids->end());
}
/// See if any reapable processes have exited, and mark them accordingly.
/// \param block_ok if no reapable processes have exited, block until one is (or until we receive a
/// signal).
@ -374,13 +385,8 @@ static void process_mark_finished_children(parser_t &parser, bool block_ok) {
}
}
// Poll disowned processes/process groups, but do nothing with the result. Only used to avoid
// zombie processes. Entries have already been converted to negative for process groups.
int status;
s_disowned_pids.erase(
std::remove_if(s_disowned_pids.begin(), s_disowned_pids.end(),
[&status](pid_t pid) { return waitpid(pid, &status, WNOHANG) > 0; }),
s_disowned_pids.end());
// Remove any zombies.
reap_disowned_pids();
}
/// Given a command like "cat file", truncate it to a reasonable length.