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8245543: Cgroups: Incorrect detection logic on some systems (still reproducible)

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Reviewed-by: bobv, shade
This commit is contained in:
Severin Gehwolf 2020-10-09 16:25:50 +00:00
parent aaa0a2a047
commit 2bbf8a2a96
4 changed files with 96 additions and 6 deletions
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61
src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemFactory.java
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@ -33,6 +33,8 @@ import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Stream;
import jdk.internal.platform.cgroupv1.CgroupV1Subsystem;
@ -46,6 +48,31 @@ public class CgroupSubsystemFactory {
private static final String BLKIO_CTRL = "blkio";
private static final String MEMORY_CTRL = "memory";
/*
* From https://www.kernel.org/doc/Documentation/filesystems/proc.txt
*
* 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
* (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
*
* (1) mount ID: unique identifier of the mount (may be reused after umount)
* (2) parent ID: ID of parent (or of self for the top of the mount tree)
* (3) major:minor: value of st_dev for files on filesystem
* (4) root: root of the mount within the filesystem
* (5) mount point: mount point relative to the process's root
* (6) mount options: per mount options
* (7) optional fields: zero or more fields of the form "tag[:value]"
* (8) separator: marks the end of the optional fields
* (9) filesystem type: name of filesystem of the form "type[.subtype]"
* (10) mount source: filesystem specific information or "none"
* (11) super options: per super block options
*/
private static final Pattern MOUNTINFO_PATTERN = Pattern.compile(
"^[^\\s]+\\s+[^\\s]+\\s+[^\\s]+\\s+" + // (1), (2), (3)
"[^\\s]+\\s+([^\\s]+)\\s+" + // (4), (5) - group 1: mount point
"[^-]+-\\s+" + // (6), (7), (8)
"([^\\s]+)\\s+" + // (9) - group 2: filesystem type
".*$"); // (10), (11)
static CgroupMetrics create() {
Optional<CgroupTypeResult> optResult = null;
try {
@ -114,12 +141,13 @@ public class CgroupSubsystemFactory {
anyControllersEnabled = anyControllersEnabled || info.isEnabled();
}
// If there are no mounted controllers in mountinfo, but we've only
// seen 0 hierarchy IDs in /proc/cgroups, we are on a cgroups v1 system.
// If there are no mounted, relevant cgroup controllers in mountinfo and only
// 0 hierarchy IDs in /proc/cgroups have been seen, we are on a cgroups v1 system.
// However, continuing in that case does not make sense as we'd need
// information from mountinfo for the mounted controller paths anyway.
// information from mountinfo for the mounted controller paths which we wouldn't
// find anyway in that case.
try (Stream<String> mntInfo = CgroupUtil.readFilePrivileged(Paths.get(mountInfo))) {
boolean anyCgroupMounted = mntInfo.anyMatch(line -> line.contains("cgroup"));
boolean anyCgroupMounted = mntInfo.anyMatch(CgroupSubsystemFactory::isRelevantControllerMount);
if (!anyCgroupMounted && isCgroupsV2) {
return Optional.empty();
}
@ -128,6 +156,31 @@ public class CgroupSubsystemFactory {
return Optional.of(result);
}
private static boolean isRelevantControllerMount(String line) {
Matcher lineMatcher = MOUNTINFO_PATTERN.matcher(line.trim());
if (lineMatcher.matches()) {
String mountPoint = lineMatcher.group(1);
String fsType = lineMatcher.group(2);
if (fsType.equals("cgroup")) {
String filename = Paths.get(mountPoint).getFileName().toString();
for (String fn: filename.split(",")) {
switch (fn) {
case MEMORY_CTRL: // fall through
case CPU_CTRL:
case CPUSET_CTRL:
case CPUACCT_CTRL:
case BLKIO_CTRL:
return true;
default: break; // ignore not recognized controllers
}
}
} else if (fsType.equals("cgroup2")) {
return true;
}
}
return false;
}
public static final class CgroupTypeResult {
private final boolean isCgroupV2;
private final boolean anyControllersEnabled;