JDK14/Java14源码在线阅读
/*
* Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include <string.h>
#include <math.h>
#include <errno.h>
#include "utilities/globalDefinitions.hpp"
#include "memory/allocation.hpp"
#include "runtime/globals.hpp"
#include "runtime/os.hpp"
#include "logging/log.hpp"
#include "osContainer_linux.hpp"
/*
* PER_CPU_SHARES has been set to 1024 because CPU shares' quota
* is commonly used in cloud frameworks like Kubernetes[1],
* AWS[2] and Mesos[3] in a similar way. They spawn containers with
* --cpu-shares option values scaled by PER_CPU_SHARES. Thus, we do
* the inverse for determining the number of possible available
* CPUs to the JVM inside a container. See JDK-8216366.
*
* [1] https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/#meaning-of-cpu
* In particular:
* When using Docker:
* The spec.containers[].resources.requests.cpu is converted to its core value, which is potentially
* fractional, and multiplied by 1024. The greater of this number or 2 is used as the value of the
* --cpu-shares flag in the docker run command.
* [2] https://docs.aws.amazon.com/AmazonECS/latest/APIReference/API_ContainerDefinition.html
* [3] https://github.com/apache/mesos/blob/3478e344fb77d931f6122980c6e94cd3913c441d/src/docker/docker.cpp#L648
* https://github.com/apache/mesos/blob/3478e344fb77d931f6122980c6e94cd3913c441d/src/slave/containerizer/mesos/isolators/cgroups/constants.hpp#L30
*/
#define PER_CPU_SHARES 1024
bool OSContainer::_is_initialized = false;
bool OSContainer::_is_containerized = false;
int OSContainer::_active_processor_count = 1;
julong _unlimited_memory;
class CgroupSubsystem: CHeapObj<mtInternal> {
friend class OSContainer;
private:
volatile jlong _next_check_counter;
/* mountinfo contents */
char *_root;
char *_mount_point;
/* Constructed subsystem directory */
char *_path;
public:
CgroupSubsystem(char *root, char *mountpoint) {
_root = os::strdup(root);
_mount_point = os::strdup(mountpoint);
_path = NULL;
_next_check_counter = min_jlong;
}
/*
* Set directory to subsystem specific files based
* on the contents of the mountinfo and cgroup files.
*/
void set_subsystem_path(char *cgroup_path) {
char buf[MAXPATHLEN+1];
if (_root != NULL && cgroup_path != NULL) {
if (strcmp(_root, "/") == 0) {
int buflen;
strncpy(buf, _mount_point, MAXPATHLEN);
buf[MAXPATHLEN-1] = '\0';
if (strcmp(cgroup_path,"/") != 0) {
buflen = strlen(buf);
if ((buflen + strlen(cgroup_path)) > (MAXPATHLEN-1)) {
return;
}
strncat(buf, cgroup_path, MAXPATHLEN-buflen);
buf[MAXPATHLEN-1] = '\0';
}
_path = os::strdup(buf);
} else {
if (strcmp(_root, cgroup_path) == 0) {
strncpy(buf, _mount_point, MAXPATHLEN);
buf[MAXPATHLEN-1] = '\0';
_path = os::strdup(buf);
} else {
char *p = strstr(cgroup_path, _root);
if (p != NULL && p == _root) {
if (strlen(cgroup_path) > strlen(_root)) {
int buflen;
strncpy(buf, _mount_point, MAXPATHLEN);
buf[MAXPATHLEN-1] = '\0';
buflen = strlen(buf);
if ((buflen + strlen(cgroup_path) - strlen(_root)) > (MAXPATHLEN-1)) {
return;
}
strncat(buf, cgroup_path + strlen(_root), MAXPATHLEN-buflen);
buf[MAXPATHLEN-1] = '\0';
_path = os::strdup(buf);
}
}
}
}
}
}
char *subsystem_path() { return _path; }
bool cache_has_expired() {
return os::elapsed_counter() > _next_check_counter;
}
void set_cache_expiry_time(jlong timeout) {
_next_check_counter = os::elapsed_counter() + timeout;
}
};
class CgroupMemorySubsystem: CgroupSubsystem {
friend class OSContainer;
private:
/* Some container runtimes set limits via cgroup
* hierarchy. If set to true consider also memory.stat
* file if everything else seems unlimited */
bool _uses_mem_hierarchy;
volatile jlong _memory_limit_in_bytes;
public:
CgroupMemorySubsystem(char *root, char *mountpoint) : CgroupSubsystem::CgroupSubsystem(root, mountpoint) {
_uses_mem_hierarchy = false;
_memory_limit_in_bytes = -1;
}
bool is_hierarchical() { return _uses_mem_hierarchy; }
void set_hierarchical(bool value) { _uses_mem_hierarchy = value; }
jlong memory_limit_in_bytes() { return _memory_limit_in_bytes; }
void set_memory_limit_in_bytes(jlong value) {
_memory_limit_in_bytes = value;
// max memory limit is unlikely to change, but we want to remain
// responsive to configuration changes. A very short grace time
// between re-read avoids excessive overhead during startup without
// significantly reducing the VMs ability to promptly react to reduced
// memory availability
set_cache_expiry_time(OSCONTAINER_CACHE_TIMEOUT);
}
};
CgroupMemorySubsystem* memory = NULL;
CgroupSubsystem* cpuset = NULL;
CgroupSubsystem* cpu = NULL;
CgroupSubsystem* cpuacct = NULL;
typedef char * cptr;
PRAGMA_DIAG_PUSH
PRAGMA_FORMAT_NONLITERAL_IGNORED
template <typename T> int subsystem_file_line_contents(CgroupSubsystem* c,
const char *filename,
const char *matchline,
const char *scan_fmt,
T returnval) {
FILE *fp = NULL;
char *p;
char file[MAXPATHLEN+1];
char buf[MAXPATHLEN+1];
char discard[MAXPATHLEN+1];
bool found_match = false;
if (c == NULL) {
log_debug(os, container)("subsystem_file_line_contents: CgroupSubsytem* is NULL");
return OSCONTAINER_ERROR;
}
if (c->subsystem_path() == NULL) {
log_debug(os, container)("subsystem_file_line_contents: subsystem path is NULL");
return OSCONTAINER_ERROR;
}
strncpy(file, c->subsystem_path(), MAXPATHLEN);
file[MAXPATHLEN-1] = '\0';
int filelen = strlen(file);
if ((filelen + strlen(filename)) > (MAXPATHLEN-1)) {
log_debug(os, container)("File path too long %s, %s", file, filename);
return OSCONTAINER_ERROR;
}
strncat(file, filename, MAXPATHLEN-filelen);
log_trace(os, container)("Path to %s is %s", filename, file);
fp = fopen(file, "r");
if (fp != NULL) {
int err = 0;
while ((p = fgets(buf, MAXPATHLEN, fp)) != NULL) {
found_match = false;
if (matchline == NULL) {
// single-line file case
int matched = sscanf(p, scan_fmt, returnval);
found_match = (matched == 1);
} else {
// multi-line file case
if (strstr(p, matchline) != NULL) {
// discard matchline string prefix
int matched = sscanf(p, scan_fmt, discard, returnval);
found_match = (matched == 2);
} else {
continue; // substring not found
}
}
if (found_match) {
fclose(fp);
return 0;
} else {
err = 1;
log_debug(os, container)("Type %s not found in file %s", scan_fmt, file);
}
}
if (err == 0) {
log_debug(os, container)("Empty file %s", file);
}
} else {
log_debug(os, container)("Open of file %s failed, %s", file, os::strerror(errno));
}
if (fp != NULL)
fclose(fp);
return OSCONTAINER_ERROR;
}
PRAGMA_DIAG_POP
#define GET_CONTAINER_INFO(return_type, subsystem, filename, \
logstring, scan_fmt, variable) \
return_type variable; \
{ \
int err; \
err = subsystem_file_line_contents(subsystem, \
filename, \
NULL, \
scan_fmt, \
&variable); \
if (err != 0) \
return (return_type) OSCONTAINER_ERROR; \
\
log_trace(os, container)(logstring, variable); \
}
#define GET_CONTAINER_INFO_CPTR(return_type, subsystem, filename, \
logstring, scan_fmt, variable, bufsize) \
char variable[bufsize]; \
{ \
int err; \
err = subsystem_file_line_contents(subsystem, \
filename, \
NULL, \
scan_fmt, \
variable); \
if (err != 0) \
return (return_type) NULL; \
\
log_trace(os, container)(logstring, variable); \
}
#define GET_CONTAINER_INFO_LINE(return_type, subsystem, filename, \
matchline, logstring, scan_fmt, variable) \
return_type variable; \
{ \
int err; \
err = subsystem_file_line_contents(subsystem, \
filename, \
matchline, \
scan_fmt, \
&variable); \
if (err != 0) \
return (return_type) OSCONTAINER_ERROR; \
\
log_trace(os, container)(logstring, variable); \
}
/* init
*
* Initialize the container support and determine if
* we are running under cgroup control.
*/
void OSContainer::init() {
FILE *mntinfo = NULL;
FILE *cgroup = NULL;
char buf[MAXPATHLEN+1];
char tmproot[MAXPATHLEN+1];
char tmpmount[MAXPATHLEN+1];
char *p;
jlong mem_limit;
assert(!_is_initialized, "Initializing OSContainer more than once");
_is_initialized = true;
_is_containerized = false;
_unlimited_memory = (LONG_MAX / os::vm_page_size()) * os::vm_page_size();
log_trace(os, container)("OSContainer::init: Initializing Container Support");
if (!UseContainerSupport) {
log_trace(os, container)("Container Support not enabled");
return;
}
/*
* Find the cgroup mount point for memory and cpuset
* by reading /proc/self/mountinfo
*
* Example for docker:
* 219 214 0:29 /docker/7208cebd00fa5f2e342b1094f7bed87fa25661471a4637118e65f1c995be8a34 /sys/fs/cgroup/memory ro,nosuid,nodev,noexec,relatime - cgroup cgroup rw,memory
*
* Example for host:
* 34 28 0:29 / /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime shared:16 - cgroup cgroup rw,memory
*/
mntinfo = fopen("/proc/self/mountinfo", "r");
if (mntinfo == NULL) {
log_debug(os, container)("Can't open /proc/self/mountinfo, %s",
os::strerror(errno));
return;
}
while ((p = fgets(buf, MAXPATHLEN, mntinfo)) != NULL) {
char tmpcgroups[MAXPATHLEN+1];
char *cptr = tmpcgroups;
char *token;
// mountinfo format is documented at https://www.kernel.org/doc/Documentation/filesystems/proc.txt
if (sscanf(p, "%*d %*d %*d:%*d %s %s %*[^-]- cgroup %*s %s", tmproot, tmpmount, tmpcgroups) != 3) {
continue;
}
while ((token = strsep(&cptr, ",")) != NULL) {
if (strcmp(token, "memory") == 0) {
memory = new CgroupMemorySubsystem(tmproot, tmpmount);
} else if (strcmp(token, "cpuset") == 0) {
cpuset = new CgroupSubsystem(tmproot, tmpmount);
} else if (strcmp(token, "cpu") == 0) {
cpu = new CgroupSubsystem(tmproot, tmpmount);
} else if (strcmp(token, "cpuacct") == 0) {
cpuacct= new CgroupSubsystem(tmproot, tmpmount);
}
}
}
fclose(mntinfo);
if (memory == NULL) {
log_debug(os, container)("Required cgroup memory subsystem not found");
return;
}
if (cpuset == NULL) {
log_debug(os, container)("Required cgroup cpuset subsystem not found");
return;
}
if (cpu == NULL) {
log_debug(os, container)("Required cgroup cpu subsystem not found");
return;
}
if (cpuacct == NULL) {
log_debug(os, container)("Required cgroup cpuacct subsystem not found");
return;
}
/*
* Read /proc/self/cgroup and map host mount point to
* local one via /proc/self/mountinfo content above
*
* Docker example:
* 5:memory:/docker/6558aed8fc662b194323ceab5b964f69cf36b3e8af877a14b80256e93aecb044
*
* Host example:
* 5:memory:/user.slice
*
* Construct a path to the process specific memory and cpuset
* cgroup directory.
*
* For a container running under Docker from memory example above
* the paths would be:
*
* /sys/fs/cgroup/memory
*
* For a Host from memory example above the path would be:
*
* /sys/fs/cgroup/memory/user.slice
*
*/
cgroup = fopen("/proc/self/cgroup", "r");
if (cgroup == NULL) {
log_debug(os, container)("Can't open /proc/self/cgroup, %s",
os::strerror(errno));
return;
}
while ((p = fgets(buf, MAXPATHLEN, cgroup)) != NULL) {
char *controllers;
char *token;
char *base;
/* Skip cgroup number */
strsep(&p, ":");
/* Get controllers and base */
controllers = strsep(&p, ":");
base = strsep(&p, "\n");
if (controllers == NULL) {
continue;
}
while ((token = strsep(&controllers, ",")) != NULL) {
if (strcmp(token, "memory") == 0) {
memory->set_subsystem_path(base);
jlong hierarchy = uses_mem_hierarchy();
if (hierarchy > 0) {
memory->set_hierarchical(true);
}
} else if (strcmp(token, "cpuset") == 0) {
cpuset->set_subsystem_path(base);
} else if (strcmp(token, "cpu") == 0) {
cpu->set_subsystem_path(base);
} else if (strcmp(token, "cpuacct") == 0) {
cpuacct->set_subsystem_path(base);
}
}
}
fclose(cgroup);
// We need to update the amount of physical memory now that
// command line arguments have been processed.
if ((mem_limit = memory_limit_in_bytes()) > 0) {
os::Linux::set_physical_memory(mem_limit);
log_info(os, container)("Memory Limit is: " JLONG_FORMAT, mem_limit);
}
_is_containerized = true;
}
const char * OSContainer::container_type() {
if (is_containerized()) {
return "cgroupv1";
} else {
return NULL;
}
}
/* uses_mem_hierarchy
*
* Return whether or not hierarchical cgroup accounting is being
* done.
*
* return:
* A number > 0 if true, or
* OSCONTAINER_ERROR for not supported
*/
jlong OSContainer::uses_mem_hierarchy() {
GET_CONTAINER_INFO(jlong, memory, "/memory.use_hierarchy",
"Use Hierarchy is: " JLONG_FORMAT, JLONG_FORMAT, use_hierarchy);
return use_hierarchy;
}
/* memory_limit_in_bytes
*
* Return the limit of available memory for this process.
*
* return:
* memory limit in bytes or
* -1 for unlimited
* OSCONTAINER_ERROR for not supported
*/
jlong OSContainer::memory_limit_in_bytes() {
if (!memory->cache_has_expired()) {
return memory->memory_limit_in_bytes();
}
jlong memory_limit = read_memory_limit_in_bytes();
// Update CgroupMemorySubsystem to avoid re-reading container settings too often
memory->set_memory_limit_in_bytes(memory_limit);
return memory_limit;
}
jlong OSContainer::read_memory_limit_in_bytes() {
GET_CONTAINER_INFO(julong, memory, "/memory.limit_in_bytes",
"Memory Limit is: " JULONG_FORMAT, JULONG_FORMAT, memlimit);
if (memlimit >= _unlimited_memory) {
log_trace(os, container)("Non-Hierarchical Memory Limit is: Unlimited");
if (memory->is_hierarchical()) {
const char* matchline = "hierarchical_memory_limit";
const char* format = "%s " JULONG_FORMAT;
GET_CONTAINER_INFO_LINE(julong, memory, "/memory.stat", matchline,
"Hierarchical Memory Limit is: " JULONG_FORMAT, format, hier_memlimit)
if (hier_memlimit >= _unlimited_memory) {
log_trace(os, container)("Hierarchical Memory Limit is: Unlimited");
} else {
return (jlong)hier_memlimit;
}
}
return (jlong)-1;
}
else {
return (jlong)memlimit;
}
}
jlong OSContainer::memory_and_swap_limit_in_bytes() {
GET_CONTAINER_INFO(julong, memory, "/memory.memsw.limit_in_bytes",
"Memory and Swap Limit is: " JULONG_FORMAT, JULONG_FORMAT, memswlimit);
if (memswlimit >= _unlimited_memory) {
log_trace(os, container)("Non-Hierarchical Memory and Swap Limit is: Unlimited");
if (memory->is_hierarchical()) {
const char* matchline = "hierarchical_memsw_limit";
const char* format = "%s " JULONG_FORMAT;
GET_CONTAINER_INFO_LINE(julong, memory, "/memory.stat", matchline,
"Hierarchical Memory and Swap Limit is : " JULONG_FORMAT, format, hier_memlimit)
if (hier_memlimit >= _unlimited_memory) {
log_trace(os, container)("Hierarchical Memory and Swap Limit is: Unlimited");
} else {
return (jlong)hier_memlimit;
}
}
return (jlong)-1;
} else {
return (jlong)memswlimit;
}
}
jlong OSContainer::memory_soft_limit_in_bytes() {
GET_CONTAINER_INFO(julong, memory, "/memory.soft_limit_in_bytes",
"Memory Soft Limit is: " JULONG_FORMAT, JULONG_FORMAT, memsoftlimit);
if (memsoftlimit >= _unlimited_memory) {
log_trace(os, container)("Memory Soft Limit is: Unlimited");
return (jlong)-1;
} else {
return (jlong)memsoftlimit;
}
}
/* memory_usage_in_bytes
*
* Return the amount of used memory for this process.
*
* return:
* memory usage in bytes or
* -1 for unlimited
* OSCONTAINER_ERROR for not supported
*/
jlong OSContainer::memory_usage_in_bytes() {
GET_CONTAINER_INFO(jlong, memory, "/memory.usage_in_bytes",
"Memory Usage is: " JLONG_FORMAT, JLONG_FORMAT, memusage);
return memusage;
}
/* memory_max_usage_in_bytes
*
* Return the maximum amount of used memory for this process.
*
* return:
* max memory usage in bytes or
* OSCONTAINER_ERROR for not supported
*/
jlong OSContainer::memory_max_usage_in_bytes() {
GET_CONTAINER_INFO(jlong, memory, "/memory.max_usage_in_bytes",
"Maximum Memory Usage is: " JLONG_FORMAT, JLONG_FORMAT, memmaxusage);
return memmaxusage;
}
/* active_processor_count
*
* Calculate an appropriate number of active processors for the
* VM to use based on these three inputs.
*
* cpu affinity
* cgroup cpu quota & cpu period
* cgroup cpu shares
*
* Algorithm:
*
* Determine the number of available CPUs from sched_getaffinity
*
* If user specified a quota (quota != -1), calculate the number of
* required CPUs by dividing quota by period.
*
* If shares are in effect (shares != -1), calculate the number
* of CPUs required for the shares by dividing the share value
* by PER_CPU_SHARES.
*
* All results of division are rounded up to the next whole number.
*
* If neither shares or quotas have been specified, return the
* number of active processors in the system.
*
* If both shares and quotas have been specified, the results are
* based on the flag PreferContainerQuotaForCPUCount. If true,
* return the quota value. If false return the smallest value
* between shares or quotas.
*
* If shares and/or quotas have been specified, the resulting number
* returned will never exceed the number of active processors.
*
* return:
* number of CPUs
*/
int OSContainer::active_processor_count() {
int quota_count = 0, share_count = 0;
int cpu_count, limit_count;
int result;
// We use a cache with a timeout to avoid performing expensive
// computations in the event this function is called frequently.
// [See 8227006].
if (!cpu->cache_has_expired()) {
log_trace(os, container)("OSContainer::active_processor_count (cached): %d", OSContainer::_active_processor_count);
return OSContainer::_active_processor_count;
}
cpu_count = limit_count = os::Linux::active_processor_count();
int quota = cpu_quota();
int period = cpu_period();
int share = cpu_shares();
if (quota > -1 && period > 0) {
quota_count = ceilf((float)quota / (float)period);
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