Michal Privoznik wrote:
> On 13.11.2014 03:36, Jim Fehlig wrote:
>> The libxl driver receives migration data within an IO callback invoked
>> by the event loop, effectively disabling the event loop while migration
>> occurs.
>>
>> This patch moves receving of the migration data to a thread. The
>> incoming connection is still accepted in the IO callback, but control
>> is immediately returned to the event loop after spawning the thread.
>>
>> Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
>> ---
>> src/libxl/libxl_migration.c | 60
>> +++++++++++++++++++++++++++++++--------------
>> 1 file changed, 42 insertions(+), 18 deletions(-)
>>
>> diff --git a/src/libxl/libxl_migration.c b/src/libxl/libxl_migration.c
>> index 0b562f7..1940209 100644
>> --- a/src/libxl/libxl_migration.c
>> +++ b/src/libxl/libxl_migration.c
>> @@ -35,6 +35,7 @@
>> #include "vircommand.h"
>> #include "virstring.h"
>> #include "virobject.h"
>> +#include "virthread.h"
>> #include "rpc/virnetsocket.h"
>> #include "libxl_domain.h"
>> #include "libxl_driver.h"
>> @@ -48,6 +49,7 @@ VIR_LOG_INIT("libxl.libxl_migration");
>> typedef struct _libxlMigrationDstArgs {
>> virObject parent;
>>
>> + int recvfd;
>> virConnectPtr conn;
>> virDomainObjPtr vm;
>> unsigned int flags;
>> @@ -82,31 +84,18 @@ libxlMigrationDstArgsOnceInit(void)
>> VIR_ONCE_GLOBAL_INIT(libxlMigrationDstArgs)
>>
>> static void
>> -libxlDoMigrateReceive(virNetSocketPtr sock,
>> - int events ATTRIBUTE_UNUSED,
>> - void *opaque)
>> +libxlDoMigrateReceive(void *opaque)
>> {
>> libxlMigrationDstArgs *args = opaque;
>> - virConnectPtr conn = args->conn;
>> virDomainObjPtr vm = args->vm;
>> virNetSocketPtr *socks = args->socks;
>> size_t nsocks = args->nsocks;
>> bool paused = args->flags & VIR_MIGRATE_PAUSED;
>> - libxlDriverPrivatePtr driver = conn->privateData;
>> - virNetSocketPtr client_sock;
>> - int recvfd = -1;
>> + libxlDriverPrivatePtr driver = args->conn->privateData;
>> + int recvfd = args->recvfd;
>> size_t i;
>> int ret;
>>
>> - if (virNetSocketAccept(sock, &client_sock) < 0) {
>> - virReportError(VIR_ERR_OPERATION_INVALID, "%s",
>> - _("Fail to accept migration connection"));
>> - goto cleanup;
>> - }
>> - VIR_DEBUG("Accepted migration connection\n");
>> - recvfd = virNetSocketDupFD(client_sock, true);
>> - virObjectUnref(client_sock);
>> -
>> virObjectLock(vm);
>> ret = libxlDomainStart(driver, vm, paused, recvfd);
>> virObjectUnlock(vm);
>> @@ -114,7 +103,6 @@ libxlDoMigrateReceive(virNetSocketPtr sock,
>> if (ret < 0 && !vm->persistent)
>> virDomainObjListRemove(driver->domains, vm);
>>
>> - cleanup:
>> /* Remove all listen socks from event handler, and close them. */
>> for (i = 0; i < nsocks; i++) {
>> virNetSocketUpdateIOCallback(socks[i], 0);
>> @@ -127,6 +115,42 @@ libxlDoMigrateReceive(virNetSocketPtr sock,
>> VIR_FORCE_CLOSE(recvfd);
>> }
>>
>> +
>> +static void
>> +libxlMigrateReceive(virNetSocketPtr sock,
>> + int events ATTRIBUTE_UNUSED,
>> + void *opaque)
>> +{
>> + libxlMigrationDstArgs *args = opaque;
>> + virNetSocketPtr client_sock;
>> + int recvfd;
>> + virThread thread;
>> +
>> + /* Accept migration connection */
>> + virNetSocketAccept(sock, &client_sock);
>> + if (client_sock == NULL) {
>> + virReportError(VIR_ERR_OPERATION_FAILED, "%s",
>> + _("Failed to accept migration connection"));
>> + return;
>> + }
>> + VIR_DEBUG("Accepted migration connection."
>> + " Spawing thread to process migration data");
>> + recvfd = virNetSocketDupFD(client_sock, true);
>> + virObjectUnref(client_sock);
>> +
>> + /*
>> + * Avoid blocking the event loop. Start a thread to receive
>> + * the migration data
>> + */
>> + args->recvfd = recvfd;
>> + if (virThreadCreate(&thread, false,
>> + libxlDoMigrateReceive, args) < 0) {
>> + virReportError(VIR_ERR_OPERATION_FAILED, "%s",
>> + _("Failed to create thread for receiving
>> migration data"));
>
> I believe you want VIR_FORCE_CLOSE(args->recvfd) in case thread
> creation failed.
Ah, yes, thanks for catching that. In fact, I need to cleanup all the
listening sockets on failure too.
Also, while reordering this series I mistakenly dropped a patch that
fixes a race condition introduced by moving the receive processing to a
thread.
V2 on the way. Sorry for wasting your time on an incomplete V1.
Regards,
Jim
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