Damans227 commented on code in PR #14189:
URL: https://github.com/apache/cloudstack/pull/14189#discussion_r4168153283
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plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/LibvirtStorageAdaptor.java:
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@@ -700,40 +708,45 @@ public KVMPhysicalDisk getPhysicalDisk(String volumeUuid,
KVMStoragePool pool) {
* adjust refcount
*/
private int adjustStoragePoolRefCount(String uuid, int adjustment) {
- final String mutexKey = storagePoolRefCounts.keySet().stream()
- .filter(k -> k.equals(uuid))
- .findFirst()
- .orElse(uuid);
- synchronized (mutexKey) {
- // some access on the storagePoolRefCounts.key(mutexKey) element
- int refCount = storagePoolRefCounts.computeIfAbsent(mutexKey, k ->
0);
- refCount += adjustment;
- if (refCount < 1) {
- storagePoolRefCounts.remove(mutexKey);
- } else {
- storagePoolRefCounts.put(mutexKey, refCount);
- }
- return refCount;
- }
+ /*
+ * compute() is atomic for the key, so concurrent callers cannot lose
an
+ * update. Returning null from the remapping function removes the
entry,
+ * which keeps the map free of pools that are no longer in use.
+ */
+ Integer refCount = storagePoolRefCounts.compute(uuid, (key, count) -> {
+ int adjusted = (count == null ? 0 : count) + adjustment;
+ return adjusted < 1 ? null : adjusted;
+ });
+ return refCount == null ? 0 : refCount;
}
/**
* Thread-safe increment storage pool usage refcount
* @param uuid UUID of the storage pool to increment the count
*/
- private void incStoragePoolRefCount(String uuid) {
+ protected void incStoragePoolRefCount(String uuid) {
adjustStoragePoolRefCount(uuid, 1);
}
/**
* Thread-safe decrement storage pool usage refcount for the given uuid
and return if storage pool still in use.
* @param uuid UUID of the storage pool to decrement the count
* @return true if the storage pool is still used, else false.
*/
- private boolean decStoragePoolRefCount(String uuid) {
+ protected boolean decStoragePoolRefCount(String uuid) {
return adjustStoragePoolRefCount(uuid, -1) > 0;
}
+ private static Object getStoragePoolLock(String uuid) {
+ return storagePoolLocks.computeIfAbsent(uuid, k -> new Object());
+ }
+
@Override
public KVMStoragePool createStoragePool(String name, String host, int
port, String path, String userInfo, StoragePoolType type, Map<String, String>
details, boolean isPrimaryStorage) {
+ synchronized (getStoragePoolLock(name)) {
Review Comment:
if an unmount hangs, could this hold up every other pool on the host too? a
create for the same pool waits here while still holding the manager wide lock
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