<div dir="ltr"><div>Yes, obviously using implementation with poll() is much better practice than select(), but my problem seems to be a little different. The problem that I face is that I run out of file descriptors after certain number of calls to loop(). </div><div>Each call consumes few fd's which seem to be closed properly. But in fact these fd's are never reused and I can see them piling in /proc/{pid}/fdinfo. My implementation does not use many fd's, problem is that they stay open and are not reused. Eventually I run out of fd's and face to buffer overflow crash. </div></div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Feb 26, 2020 at 12:59 PM Pino Toscano <<a href="mailto:ptoscano@redhat.com">ptoscano@redhat.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Wednesday, 26 February 2020 10:43:27 CET Richard W.M. Jones wrote: > On Wed, Feb 26, 2020 at 11:21:18AM +0200, Veselin Kozhuharski wrote: > > Hallo Rich, > > > > Here is the fd list and total number just before collectd application > > crashes. Before that the number of used fd's is constantly increasing. It > > looks like a fd leak inside libguestfs to me. I am trying to debug the fd > > handling inside the library. > > > > root@localhost:~# less /proc/8829/fdinfo/ > > Display all 1035 possibilities? (y or n) > > 0 1029 129 161 193 224 256 288 319 350 382 413 445 > > 477 508 54 571 602 634 666 698 729 760 792 823 > > 855 887 918 95 981 > > 1 103 13 162 194 225 257 289 32 351 383 414 446 > > 478 509 540 572 603 635 667 699 73 761 793 824 > > 856 888 919 950 982 > > 10 1030 130 163 195 226 258 29 320 352 384 415 447 > > 479 51 541 573 604 636 668 7 730 762 794 825 > > 857 889 92 951 983 > > 100 1031 131 164 196 227 259 290 321 353 385 416 448 > > 48 510 542 574 605 637 669 70 731 763 795 826 > > 858 89 920 952 984 > > 1000 1032 132 165 197 228 26 291 322 354 386 417 449 > > 480 511 543 575 606 638 67 700 732 764 796 827 > > 859 890 921 953 985 > > 1001 1033 133 166 198 229 260 292 323 355 387 418 45 > > 481 512 544 576 607 639 670 701 733 765 797 828 > > 86 891 922 954 986 > > 1002 1034 134 167 199 23 261 293 324 356 388 419 450 > > 482 513 545 577 608 64 671 702 734 766 798 829 > > 860 892 923 955 987 > > 1003 1035 135 168 2 230 262 294 325 357 389 42 451 > > 483 514 546 578 609 640 672 703 735 767 799 83 > > 861 893 924 956 988 > > 1004 104 136 169 20 231 263 295 326 358 39 420 452 > > 484 515 547 579 61 641 673 704 736 768 8 830 > > 862 894 925 957 989 > > 1005 105 137 17 200 232 264 296 327 359 390 421 453 > > 485 516 548 58 610 642 674 705 737 769 80 831 > > 863 895 926 958 99 > > 1006 106 138 170 201 233 265 297 328 36 391 422 454 > > 486 517 549 580 611 643 675 706 738 77 800 832 > > 864 896 927 959 990 > > 1007 107 139 171 202 234 266 298 329 360 392 423 455 > > 487 518 55 581 612 644 676 707 739 770 801 833 > > 865 897 928 96 991 > > 1008 108 14 172 203 235 267 299 33 361 393 424 456 > > 488 519 550 582 613 645 677 708 74 771 802 834 > > 866 898 929 960 992 > > 1009 109 140 173 204 236 268 3 330 362 394 425 457 > > 489 52 551 583 614 646 678 709 740 772 803 835 > > 867 899 93 961 993 > > 101 11 141 174 205 237 269 30 331 363 395 426 458 > > 49 520 552 584 615 647 679 71 741 773 804 836 > > 868 9 930 962 994 > > 1010 110 142 175 206 238 27 300 332 364 396 427 459 > > 490 521 553 585 616 648 68 710 742 774 805 837 > > 869 90 931 963 995 > > 1011 111 143 176 207 239 270 301 333 365 397 428 46 > > 491 522 554 586 617 649 680 711 743 775 806 838 > > 87 900 932 964 996 > > 1012 112 144 177 208 24 271 302 334 366 398 429 460 > > 492 523 555 587 618 65 681 712 744 776 807 839 > > 870 901 933 965 997 > > 1013 113 145 178 209 240 272 303 335 367 399 43 461 > > 493 524 556 588 619 650 682 713 745 777 808 84 > > 871 902 934 966 998 > > 1014 114 146 179 21 241 273 304 336 368 4 430 462 > > 494 525 557 589 62 651 683 714 746 778 809 840 > > 872 903 935 967 999 > > 1015 115 147 18 210 242 274 305 337 369 40 431 463 > > 495 526 558 59 620 652 684 715 747 779 81 841 > > 873 904 936 968 > > 1016 116 148 180 211 243 275 306 338 37 400 432 464 > > 496 527 559 590 621 653 685 716 748 78 810 842 > > 874 905 937 969 > > 1017 117 149 181 212 244 276 307 339 370 401 433 465 > > 497 528 56 591 622 654 686 717 749 780 811 843 > > 875 906 938 97 > > 1018 118 150 182 213 245 277 308 34 371 402 434 466 > > 498 529 560 592 623 655 687 718 75 781 812 844 > > 876 907 939 970 > > 1019 119 151 183 214 246 278 309 340 372 403 435 467 > > 499 53 561 593 624 656 688 719 750 782 813 845 > > 877 908 94 971 > > 102 12 152 184 215 247 279 31 341 373 404 436 468 > > 5 530 562 594 625 657 689 72 751 783 814 846 > > 878 909 940 972 > > 1020 120 153 185 216 248 28 310 342 374 405 437 469 > > 50 531 563 595 626 658 69 720 752 784 815 847 > > 879 91 941 973 > > 1021 121 154 186 217 249 280 311 343 375 406 438 47 > > 500 532 564 596 627 659 690 721 753 785 816 848 > > 88 910 942 974 > > 1022 122 155 187 218 25 281 312 344 376 407 439 470 > > 501 533 565 597 628 66 691 722 754 786 817 849 > > 880 911 943 975 > > 1023 123 156 188 219 250 282 313 345 377 408 44 471 > > 502 534 566 598 629 660 692 723 755 787 818 85 > > 881 912 944 976 > > 1024 124 157 189 22 251 283 314 346 378 409 440 472 > > 503 535 567 599 63 661 693 724 756 788 819 850 > > 882 913 945 977 > > 1025 125 158 19 220 252 284 315 347 379 41 441 473 > > 504 536 568 6 630 662 694 725 757 789 82 851 > > 883 914 946 978 > > 1026 126 159 190 221 253 285 316 348 38 410 442 474 > > 505 537 569 60 631 663 695 726 758 79 820 852 > > 884 915 947 979 > > 1027 127 16 191 222 254 286 317 349 380 411 443 475 > > 506 538 57 600 632 664 696 727 759 790 821 853 > > 885 916 948 98 > > 1028 128 160 192 223 255 287 318 35 381 412 444 476 > > 507 539 570 601 633 665 697 728 76 791 822 854 > > 886 917 949 980 > > > > Do you suspect any particular handling inside libguestfs? > > Thanks! > > Yes I guess the select() function here needs to be replaced with poll(). > > <a href="https://github.com/libguestfs/libguestfs/blob/d9b4e3086e11b18dfc5215a7c4c21ae637be4fe6/lib/command.c#L651" rel="noreferrer" target="_blank">https://github.com/libguestfs/libguestfs/blob/d9b4e3086e11b18dfc5215a7c4c21ae637be4fe6/lib/command.c#L651</a> Indeed, we ought to. I'll try to get it converted. Also, note for libguestfs people: select() is used also in the daemon, although that should not be a problem, since it does not use many libraries, and in general has few fd's opened at runtime. Note that collectd needs similar fixes, as I read in its bug tracker: <a href="https://github.com/collectd/collectd/pull/3363" rel="noreferrer" target="_blank">https://github.com/collectd/collectd/pull/3363</a> -- Pino Toscano</blockquote></div> -- <div dir="ltr" class="gmail_signature"> <table width="481" cellspacing="0" cellpadding="8"> <colgroup><col width="465"> </colgroup><tbody><tr> <td style="border:medium none;padding:0in" width="465" height="3" bgcolor="#f2f2f2"> Veselin Kozhuharski | Software Engineer </td> </tr> <tr> <td style="border:medium none;padding:0in" width="465" height="3" bgcolor="#f2f2f2"> Direct: +359 2 439 2590 ext. 3912 | Mobile: +359 887 412116 | veselin_k<a href="mailto:mzabaruk@telco.com" target="_blank">@telco.com</a> </td> </tr> <tr> <td style="border:medium none;padding:0in" width="465" height="3" bgcolor="#f05a23"> Telco Systems | <a href="http://www.telco.com/" target="_blank">www.telco.com</a> </td> </tr> <tr> <td style="border:medium none;padding:0in" width="465" height="3" bgcolor="#f2f2f2"> Follow us: <a href="http://www.linkedin.com/company/telco-systems" target="_blank">LinkedIn</a> | <a href="http://twitter.com/TelcoSystems" target="_blank">Twitter</a> | <a href="https://www.facebook.com/TelcoSystems" target="_blank">Facebook</a> | <a href="http://www.youtube.com/TelcoSystems" target="_blank">YouTube</a> | <a href="http://www.telco.com/blog" target="_blank">Blog</a> | </td> </tr> </tbody></table> </div>